Overview

Down syndrome, also known as trisomy 21, is the most common genetic disorder causing intellectual disability and the most frequently occurring human chromosomal syndrome. Distinct features of the face, hands, and feet are common. Other congenital anomalies (e.g., heart and gastrointestinal defects) and acquired conditions (e.g., hypothyroidism, hearing impairment, and celiac disease) occur more frequently in children with Down syndrome.

Prevalence

The prevalence of Down syndrome varies by age (due to the combined impact of increasing life span and selective terminations decreasing birth prevalence) and country (because of dramatic differences in availability of prenatal testing and termination and population attitudes). The probability of having a baby with Down syndrome increases as the mother’s age increases, but due to higher pregnancy rates in younger women, most children with Down syndrome are born to women under 35 years of age. Changes in childhood survival have impacted the age distribution of people with Down syndrome, with more individuals living into their fourth, fifth, and sixth decades.

The graph (left) is based on the National Down Syndrome Cytogenetic Register and shows pooled prevalence (per 10,000 live births) of Down syndrome by maternal age. [Mai: 2013] Prevalence would have been higher but for Down syndrome-related elective pregnancy terminations. [de: 2017] Prevalence would have been higher but for Down syndrome-related elective pregnancy terminations. A study in Atlanta found that the frequency of elective terminations following an abnormal prenatal cytogenetic test varied across race-ethnicity groups. Termination rates following identification of trisomy 21 were 5.7% in Hispanic, 15.2% in non-Hispanic black, and 32.3% in non-Hispanic white populations. [Jackson: 2014]

The estimated birth prevalence of Down syndrome among live births in the United States in 2010 was 1:826. The prevalence across all ages was estimated to be 1:1,499, and the estimated prevalence adjusted for age distribution in pediatric practice was 1:884. [de: 2017] [Bocian: 1999] In 2014 in the United Kingdom, the overall prevalence was 1:1574. [Alexander: 2016]

Genetics

Down syndrome refers to the phenotype or the pattern of physical traits, while trisomy 21 represents the genotype, i.e., the underlying chromosomal basis of the condition. In most individuals with trisomy 21, the additional chromosome results from the sporadic occurrence of nondisjunction of chromosome 21 during meiosis (>90% are of maternal origin). A small percentage (3-4%) of Down syndrome results from an unbalanced translocation between chromosome 21 and another chromosome (usually 13, 14, or 15). About 25% of these unbalanced translocations are familial; the rest are sporadic. [Bull: 2022] A smaller percentage of individuals with Down syndrome have trisomy 21 mosaicism from postzygotic nondisjunction during mitosis of the fertilized egg or from postzygotic loss of a chromosome 21 from a trisomic zygote. [Bull: 2022] In mosaicism, only some of the cells in the body have the extra #21 (usually expressed as a percentage of cells counted on the karyotype), and the remainder have the typical 46 constitution.

Prognosis

The severity of co-occurring congenital anomalies and degree of associated cognitive disability and social adaptability is variable. People with Down syndrome have an increased risk for certain medical conditions such as congenital heart defects, respiratory and hearing problems, Alzheimer’s disease, childhood leukemia, and thyroid conditions. Scientific advances in health care for these conditions and social advances in understanding the importance of educational and social interventions have substantially improved the likelihood of a productive life for individuals with Down syndrome. With the aid of a job coach, many adults with Down syndrome are employed in the private sector. Life expectancy for people with Down syndrome has increased dramatically in recent decades – from age 12 in 1949 to age 58 and older now. [de: 2017]

Practice Guidelines

Bull MJ, Trotter T, Santoro SL, Christensen C, Grout RW, Burke LW, Berry SA, Geleske TA, Holm I, Hopkin RJ, Introne WJ, Lyons MJ, Monteil DC, Scheuerle A, Stoler JM, Vergano SA, Chen E, Hamid R, Downs SM, Grout RW, Cunniff C, Parisi MA, Ralston SJ, Scott JA, Shapira SK, Spire P.
Health Supervision for Children and Adolescents With Down Syndrome.
Pediatrics. 2022;149(5). PubMed abstract / Full Text

Roles of the Medical Home

After the diagnosis of Down syndrome, the medical home should provide acute-care treatment, well-child checks, and chronic-care visits. At chronic-care visits, review progress, proactively manage problems, provide anticipatory guidance, vaccinations, and other preventive services. The medical home is pivotal in implementing screenings, evaluations, and interventions based on treatment guidelines. Management focuses on maximizing the child's capabilities at home and optimizing social inclusion. Treatment should start as early as possible, and the medical home, in collaboration with the family, should initiate and coordinate interdisciplinary care. Develop goals include optimizing growth and development and providing ongoing information to families about available interventions, community resources, evolving scientific understanding of trisomy 21, and emerging treatments. The family should be central in all decision-making.

Overview

Published guidelines for surveillance, screening, and caring for children with Down syndrome tend to focus on high prevalence issues and areas where consensus can be reached. [Bull: 2022] However, a number of issues are not well-addressed, including gastroesophageal reflux disease, constipation, frequent respiratory issues, and recognition of autism and ADHD. A comprehensive review of systems and evaluation of identified issues are key at all visits.

Pearls & Alerts for Assessment

Sleep apnea is common

Sleep apnea occurs in up to 45% of individuals with Down syndrome. The etiology may be obstructive, central, or mixed. A subset of individuals exhibits clinically significant sleep apnea without overt signs of upper airway obstruction. Children may have a normal sleep study and then have significant apnea a few years later. When obstructive sleep apnea is treated with a tonsillectomy and adenoidectomy, it improves but often does not resolve the concerns. A repeat sleep study should be performed in any situation where a child has new or persistent symptoms. See Sleep under Comorbid Conditions below.

Atlanto-axial instability (AAI) may not require treatment

While 13-14% of patients with Down syndrome show evidence of atlantoaxial instability (AAI) on X-ray, only 1-2% have symptoms that require treatment. Treatment guidelines no longer recommend screening all patients with X-rays. Rather, clinical care should focus on education for families regarding early symptoms and monitoring for the emergence of clinical signs of AAI as discussed under orthopedics. Careful questioning for symptoms and a neurologic exam should be part of any sports physical exam. Community organizations have yet to effect this change in guidelines, so some may still require X-rays.

Wheezing may not be asthma

While wheezing is common, asthma is not usually an accurate diagnosis if diagnostic criteria are accurately applied. [Watts: 2013] There should be careful consideration of other potential causes.

For the Condition

Prenatal
The 2016 American College of Obstetricians and Gynecologists (ACOG) guidelines advise offering screening, diagnostic testing options, and counseling about the risks for aneuploidy during every pregnancy prior to 20 weeks of gestation. Testing should result from informed patient choice; women have the right to decline genetic screening in a shared-decision making model. Maternal age and other risk factors must guide the interpretation of any test results. [Committee: 2016] [Bull: 2022]

• First trimester screening, available in weeks 10-13 of gestation, includes nuchal translucency (NT) measured by ultrasound, testing maternal blood for levels of pregnancy-associated plasma protein A levels (PAPP-A) and serum-free beta or total human chorionic gonadotropin (hCG).
  • NT measurement can help assess individual fetuses in multi-fetal pregnancies (e.g., twins) but is not considered sensitive or reliable as a single test.
• The Triple screen, available from 15-22 weeks of gestation, includes maternal blood levels of hCG, unconjugated estriol, and α-fetoprotein (AFP). Used in isolation, this is the least accurate screening method.
• The Quad screen, available from 15-22 weeks of gestation (ideally in weeks 16-18), incorporates assessing maternal blood levels of hCG, unconjugated estriol, α-fetoprotein (AFP), and dimeric inhibin A levels. The "Penta" screen adds measurement of levels of hyperglycosylated hCG (also known as invasive trophoblast antigen).
• Integrated screening is a 2-step process that combines NT measurement with serum measures from the triple and quad screening. "Serum integrated" utilizes the same blood screening but does not include NT. Results of integrated screening are not available until the second trimester.
• Sequential (stepwise or contingent) screening is like integrated screening, except the first trimester risk assessment is used to tailor subsequent screens and diagnostic testing. This approach enables decision-making in the first trimester.
• Cell-free DNA testing has rapidly become the most used screen for aneuploidy. It is performed starting at 10 weeks and is the only screen available for use in the third trimester. This method analyzes segments of placental DNA found in maternal blood. It can be quite effective at detecting trisomy 21 in high-risk populations (those with high pre-test probability), but false positives are increased in low-risk populations. In the last 5 years in the US, noninvasive prenatal screening (NIPS) using cell-free DNA testing has replaced most of the modalities mentioned above. Sensitivity, specificity, and positive predictive values have increased in recent analyses. [Badeau: 2017]
• Pre-implantation genetic screening can be used during in vitro fertilization (IVF).

None of these screening tests are considered diagnostic. Mothers with positive screens should be offered diagnostic testing with amniocentesis.

Diagnostic evaluations are more invasive because they require obtaining fetal tissue samples for genetic testing. Rates of loss associated with these procedures are 0.1% to 0.3% when performed by experienced providers. [American: 2016] Chorionic villus sampling is done at 10-13 weeks, or amniocentesis is usually performed at 15-20 weeks but can be done later. Testing embryonic tissue is also feasible prior to implantation during in vitro fertilization.

Of Family Members

In standard trisomy 21, the risk of recurrence for parents of a child with Down syndrome where the mother is less than 35 years of age is 1-2%. The reason for this increased risk is unknown; the figure is empirically determined. If the mother of the child with Down syndrome is >35 years, then the risk of recurrence is considered the same as the specific maternal age risk for the population. Less than 5% of confirmed Down syndrome diagnoses are due to a translocation and potentially carry a higher risk of recurrence. [Bull: 2022] If a child with Down syndrome has a chromosomal translocation, it is important to determine if the parents carry a balanced translocation in order to provide counseling about the recurrence risk in future pregnancies and determine if other family members should be tested.

For Complications

The most recent guidelines [Bull: 2022] provide recommendations for universal and symptom-based screening of newborns and children with Down syndrome for a wide range of comorbid conditions. These are compiled in the Down Syndrome Checklist (2022) ( 487 KB) for use in practice.

Newborn period
Universal screening

• Routine newborn screening
  • Hearing screening is adequate if ABR or OAE is normal; if abnormal, the child should be referred for follow-up evaluation.
  • Thyroid screening with thyroid stimulating hormone (TSH) is adequate; if the routine screen uses only T4, a TSH should be obtained during the nursery stay.

• Echocardiogram to evaluate for congenital heart disease (a normal fetal echo is not adequate since some heart defects can be missed, in the stable infant, the echo can be completed electively in the first weeks of life).
• Hematologic screening: Complete blood count to assess for a leukemoid reaction, myeloproliferative disorder, and polycythemia.
• Vision screening: Evaluate for cataracts with the red reflex exam.

Symptom-based screening

• Consider a car seat trial in infants with low birth weight, heart disease, or severe hypotonia.
• Consider a modified barium swallow study for newborns with feeding difficulties, respiratory concerns, or severe hypotonia.
• Assess for anorectal atresia/stenosis or Hirschsprung disease in newborns who fail to pass meconium within the first 48 hours of life.
• If clinical concerns suggest their potential, assess for intestinal atresia, airway abnormalities, obstructive sleep apnea, and gastroesophageal reflux disease.
• Routine screening for renal and urinary tract abnormalities, atlantoaxial instability, and spinal anomalies is not recommended unless indicated by symptoms (e.g., a urinary tract infection, symptoms of urinary obstruction, persistent head tilt, or torticollis).

Infancy through adolescence (refer to Down Syndrome Checklist (2022) ( 487 KB) for details and frequency of recommended screening by age). Special considerations for children with Down syndrome include:

• Hearing loss from middle ear effusion, which is often hard to visualize, is common. Some clinicians refer to ENT for routine exams to aid in monitoring.
• Eye examinations should include assessment of red reflex. Due to the high prevalence of problems (e.g., myopia, hyperopia, cataracts, strabismus, nystagmus), all children with Down syndrome should be examined by a pediatric ophthalmologist by 6 months of age. In-office photo screening is recommended, if available, after one year of age.
• All children with Down syndrome should be referred to an Early Intervention program. Bright Futures guidelines recommend standardized developmental screening (e.g., ASQ or PEDS) at 9 months of age. This should be done for any child with Down syndrome who has not been previously identified as having delays. [Committee: 2017] As many as 20-30% of children with Down syndrome will have autism spectrum disorder; clinicians should monitor for suggestive symptoms and refer for evaluation when indicated.
• Radiologic imaging for atlantoaxial instability (AAI) or spinal anomalies should be performed if symptoms suggest (e.g., persistent head tilt or torticollis, lower extremity increased reflexes). All children should be managed with the potential for AAI when positioning for intubation. Parents should be taught recommended activity restrictions (e.g., do not teach tumbling, no head-first diving, no trampoline till age 6 years and then only with supervision) and clinical signs that suggest a need for evaluation (e.g., increased tone in legs, change in gait or hand function, chronic headaches or neck pain, chronic head tilt).
• A sleep study is recommended by age 4 but should be completed sooner if any symptoms suggest obstructive or central sleep apnea.
• Consider testing for celiac disease if there is failure to thrive, chronic diarrhea, persistent constipation, chronic bloating, or iron deficiency; it is unlikely if the child has not started foods with gluten and is uncommon before age one.
• Renal/urologic studies if concerns for obstruction (e.g., posterior urethral valves) or urinary tract infection.

Presentations

Current prenatal screening will identify approximately 85-90% of fetuses with Down syndrome. A European study found that roughly 90% of mothers of affected fetuses opted to terminate pregnancy. [Morris: 2009] A meta-analysis of US studies from 1995-2011 found a weighted mean termination rate of 67% among 7 population-based studies. [Natoli: 2012] The birth of infants with Down syndrome not previously identified is becoming less common but will continue. Clinicians may be considering Down syndrome when a newborn is noted to have atypical features, hypotonia, or a major malformation associated with Down syndrome. An infant's presentation may be subtle, occasionally leading to missed diagnoses in the newborn period. These infants are likely to be recognized by the primary care clinician due to poor growth, feeding concerns, developmental delays, hypotonia, or concern for a medical condition associated with Down syndrome.

Guidelines for communicating a diagnosis of Down syndrome in the prenatal and postnatal settings can assist the provider when preparing for an informing interview. See [Skotko: 2009]; [Skotko: 2009].

Ten percent of individuals with Down syndrome are identified after 1 week of age, and more than half of those not until adulthood. Identification rates reflect past screening approaches; it is unclear how updated screening guidelines will impact this. Delayed diagnosis is more likely when an individual has mosaic trisomy 21, in which physical features may be subtle. Mosaic trisomy 21 has been identified in adult individuals with intellectual challenges but no physical features of Down syndrome.

Diagnostic Criteria

While physical features may suggest a diagnosis of Down syndrome, confirmation requires chromosome analysis, which, in most individuals, will reveal an extra chromosome 21. In 4% of patients with Down syndrome, analysis will find the attachment of an extra-long arm of chromosome 21 to another chromosome (translocation Down syndrome). A small percentage have an extra chromosome 21 in only some of their somatic cells due to loss of the extra chromosome in mitosis or nondisjunction during mitosis of the fertilized egg (mosaic Down syndrome).

Differential Diagnosis

Other genetic syndromes with overlapping features include Smith-Magenis syndrome, Zellweger syndrome, multiple X syndromes (e.g., 49,XXXXY), and Noonan syndrome.

Since many physical features of Down syndrome occasionally occur in typical infants, the clinician should look for a constellation of findings when considering the diagnosis. Epicanthal folds, protruding tongue, single palmar crease, widely-spaced first and second toes, hypotonia, and upslanting palpebral fissures are suggestive, especially in combination; however, these features can all be found in people with normal chromosomes. These issues underscore the importance of genetic testing to confirm diagnosis.

Comorbid & Secondary Conditions

Individuals with Down syndrome are at risk for many associated conditions, discussed below by organ system.

Cardiovascular
Congenital heart defects are found in around 50% of infants with Down syndrome. [Watts: 2013] [Bull: 2022] Early mortality is associated with the presence of a cardiac defect, particularly if combined with a gastrointestinal malformation. The most common defects include:

• Atrioventricular septal defects, with or without other heart defects (45%)
• Ventricular septal defects, with or without other heart defects (35%)
• Isolated secundum atrial septal defect (8%)
• Isolated persistent patent ductus arteriosus (7%)
• Isolated tetralogy of Fallot (4%)
• Other (1%)

Pulmonary hypertension may be diagnosed at birth or develop in the child with unrecognized or untreated sleep apnea or heart defect. If untreated, over the long term, pulmonary hypertension may not be reversible in the patient with an unrepaired heart defect; Eisenmenger syndrome may evolve (in which pulmonary hypertension, reversal of flow, and cyanosis develop as the left-to-right shunt switches to right-to-left (due to rising pulmonary pressures).

Acquired valvular dysfunction is common in adults with Down syndrome without congenital heart disease (up to 50%).

• Mitral valve prolapse is most common.
• Tricuspid, aortic, and mitral insufficiency have also been reported.

Nutrition

• Newborns with Down syndrome are at risk for feeding problems due to a weak suck, low tone, and problems related to organ malformations. However, many mothers who breastfeed are successful if they continue to try, especially with the guidance of a breastfeeding coach. [Aumonier: 1983] [Bull: 2022] Some infants will need significant support during the first few weeks of life to attain success with breast or bottle.
• Older infants may have lingering tongue thrust, which can delay success with the introduction of solids.
• Oral aversions are common.
• Self-feeding skills are often delayed due to delayed fine and oral motor skills, oral aversions, and behavioral challenges.
• Older children are at risk for excessive weight gain, which may be more due to family health behaviors than a characteristic of Down syndrome. [Bertapelli: 2016]
• Behavioral feeding concerns, celiac disease, reflux, chronic constipation, and diabetes are relatively common and result in an additional need to focus on nutrition.

Respiratory
Children with Down syndrome are at increased risk for recurrent acute respiratory illness, including pneumonia, aspiration, bronchiolitis syndromes, croup, and/or chronic lung disease. They are also at increased risk for sleep-related breathing disorders, including obstructive and central apnea. Contributing factors may include:

• Respiratory infections, such as pneumonia and bronchiolitis, are second only to congenital heart disease as causes for hospitalizations and are associated with increased morbidity and mortality compared to other children hospitalized for the same infections.
• Structural abnormalities - midface hypoplasia, a normal sized tongue filling a small oral cavity (thus looks large), small subglottic area, laryngomalacia, narrow nasopharynx or choanal atresia, enlarged tonsils and adenoids, tracheobronchomalacia, esophageal atresia, and tracheal stenosis. In the lungs, abnormal pulmonary vasculature, reduced number of alveoli, and enlarged alveolar ducts and alveoli may predispose these children to increased respiratory problems. Subpleural lung cysts are more commonly present, although the clinical relevance is unclear. Congenital heart disease can also predispose children to respiratory problems due to the complex interdependence of these body systems. [Watts: 2013]
• Immune deficiencies – both cellular and humoral immune differences have been described. Immunoglobin G subclasses 2 and 4 have been deficient in some children who have a normal total IgG level.
• Gastroesophageal reflux or dysphagia leading to aspiration

Wheezing may be common, but asthma is not a likely diagnosis. [Watts: 2013] It is postulated that the wheezing stems from congenital lung abnormalities, tracheomalacia, upper airway collapse secondary to hypotonia, or congenital heart disease. [Watts: 2013]

High-altitude pulmonary edema (HAPE) can occur in children with Down syndrome, especially, but not limited to those with underlying congenital heart defects, left-to-right shunts, and/or pulmonary hypertension. HAPE can be an initial sign of pulmonary hypertension. [Watts: 2013]

Sleep
Sleep apnea occurs in up to 45% of children with Down syndrome, most commonly obstructive (50-80%), although central apnea can occur. [Bull: 2022] Contributing factors may include structural abnormalities (as mentioned under Respiratory above), tonsillar/adenoidal hyperplasia, hypotonia, obesity, and brainstem dysfunction. Symptoms can include:

• Abnormal breathing patterns in sleep
• Snoring
• Abnormal sleeping positions (e.g., sitting up)
• Fragmented sleep (sometimes without snoring)
• Inattention
• Daytime sleepiness
• Difficult morning arousal (due to carbon dioxide retention)
• Early morning headaches (due to carbon dioxide retention)
• Nocturnal enuresis
• Failure to thrive
• Behavioral problems

Behavioral sleep problems, including difficulty going to sleep and staying asleep, also occur in many children with Down syndrome (as well as in kids with normal chromosomes). Providing support to parents to help them optimize sleep hygiene and manage behavioral sleep issues can be very helpful.

Gastrointestinal
The incidence of gastrointestinal anomalies in Down syndrome is higher than in the non-DS population. The most common are:

• Intestinal atresia (12% of individuals with DS) [Bull: 2022]
• Tracheoesophageal fistula
• Duodenal obstruction
• Annular pancreas
• Imperforate anus
• Hirschsprung disease (<1%) [Bull: 2022]

Individuals with Down syndrome are also at higher risk for:

• Esophageal dysmotility including achalasia [Viegelmann: 2014]
• Gastroesophageal reflux disease [Macchini: 2011]
• Constipation or intermittent diarrhea [Pavlovic: 2017]
• Gallstones [Boëchat: 2007] [Taşdemir: 2004]
• Celiac disease. (~5%) Note that about a third of individuals with Down syndrome and celiac disease have no overt clinical symptoms. [Bull: 2022] [Pavlovic: 2017] See Celiac Disease for more detail.

Hematologic
Transient asymptomatic blood count abnormalities, including neutrophilia, thrombocytopenia, and polycythemia, can occur in neonates with trisomy 21. Ten percent of infants with Down syndrome develop transient myeloproliferative disease (characterized by the presence of blasts on the smear) with spontaneous regression in the vast majority. [Bull: 2022] However, transient myeloproliferative disease can cause significant morbidity/mortality due to rare liver/heart failure, sepsis, DIC, and hyperviscosity, and 20-30% of children with Down syndrome and myeloproliferation develop lymphoid or myeloid leukemia (often delayed with a mean age onset of 20 months). [Dixon: 2006]

Individuals with Down syndrome are at increased risk for leukemia throughout childhood. Despite the increased incidence, the development of leukemia is still a relatively rare event (~1% of individuals with Down syndrome), and routine screening (beyond a complete blood count with differential at birth) is not recommended. However, follow-up CBCs over the subsequent 36 months is important for any child who has a leukemoid reaction or evidence of myeloproliferative disease on their newborn CBC, even if it appears to normalize in the newborn period.

Screening for iron deficiency is recommended in children with trisomy 21 yearly. Hemoglobin and RBC indices perform poorly (insensitive) due to baseline mild macrocytosis in many children with Down syndrome. Guidelines suggest checking a taking a dietary/medical history and checking a hemoglobin in all patients. If the dietary/medical history identifies any risk for iron deficiency, a marker of iron storage should be measured (e.g., reticulocyte hemoglobin, ferrite, serum transferrin). [Dixon: 2010]

Neurology

• Microcephaly is relatively common in trisomy 21.
• Seizures prevalence in children with Down syndrome is 1-14%. [Barca: 2014] Seizure types may include infantile spasms (West syndrome), generalized tonic-clonic seizures, partial seizures, Lennox-Gastaut, and reflex seizures. Of note, some children with Down syndrome and no clinical seizures have EEG abnormalities that may complicate interpretation.
• New-onset of focal weakness is relatively common and has a broad differential diagnosis. Etiologies found in a review of ten cases included: infarction related to Moyamoya, vaso-occlusive disease, or venous sinus thrombosis, traumatic subdural hematoma, brain abscess, spinal cord injury (from cervical spine stenosis and/or atlanto-axial instability, and brachial plexus injury. [Worley: 2004]
• Dementia - By age 40, Alzheimer-type neuropathologic abnormalities are found in all patients with Down syndrome, with or without clinical dementia. [Lott: 2012] More than half of individuals older than 50 years develop Alzheimer disease. Early-onset epilepsy is associated with decreased risk of Alzheimer, whereas late-onset epilepsy is associated with increased risk. [Menéndez: 2005]
• Myelopathy may result from atlanto-axial instability or subluxation of the occiput on C1 due to the ligamentous laxity seen in some patients with trisomy 21.

Mental Health/Behavior
“Dual diagnosis” refers to the co-existence of intellectual disability and a psychiatric disorder, which affects 18-38% of individuals with Down syndrome. [Capone: 2006] Comorbid neuropsychiatric disorders include ADHD, autism spectrum disorder, stereotypical movements, oppositional defiant and disruptive behavior disorders, anxiety, depression, obsessive-compulsive disorder, and, rarely, psychosis. A summary of behavioral disorders, their presentation and treatment can be found in the following articles: [Dykens: 2007] [Capone: 2006] Other sections of the Medical Home Portal may be helpful, including those on Autism Spectrum Disorder, Anxiety Disorders, Depression, and Attention-Deficit/Hyperactivity Disorder (ADHD).

Concerns about focus, attention span, activity level, and/or impulsiveness (Attention deficit disorder) are common. In a 2017 prevalence study in Sweden, about 1/3 of children with Down syndrome met diagnostic criteria for ADHD. [Oxelgren: 2017] Of these, many also met criteria for an autism spectrum disorder. The following should be considered in the evaluation of attention problems:

• Hearing deficits
• Vision deficits
• Thyroid disorders
• Sleep problems (e.g., sleep apnea can contribute to impaired attention)
• Impaired expressive communication
• Education setting not appropriate for cognitive level or learning style
• Emotional problems (e.g., depression, anxiety)
• Auditory processing disorders

These issues are summarized in Attention Problems in Down Syndrome: Is this ADHD? (1998, yet still useful) by Dianne McBrien, MD, a developmental pediatrician at Children's Hospital of Iowa.

Autism spectrum disorder (ASD) in children with Down syndrome is more common than previously thought when using earlier diagnostic criteria. It may be as high as 40% in children with Down syndrome and is also more common in boys than girls. [Oxelgren: 2017] Many children with Down syndrome and autism also met criteria for ADHD. Standardized autism rating scales have not been validated in those with Down syndrome. It is therefore recommended that existing DSM criteria be rigorously applied over multiple observations in different settings. Regressive autism has been noted to occur in children with Down syndrome at an older age than seen in children without Down syndrome who have an autistic regression. The accuracy or utility of a comorbid diagnosis of autism spectrum disorder in children with profound cognitive impairment (IQ<25) has been questioned. Although confirming an autism diagnosis may be more challenging in the setting of Down syndrome, a separate autism diagnosis is likely to help in accessing interventions such as applied behavioral analysis.

Depression rates in individuals with Down syndrome range from 0-11% of individuals. This rate is about the same as in the general population and in contrast to previous beliefs that people with Down syndrome are at higher risk for depression. Onset of depressive symptoms tends to occur in adulthood, although they can occur earlier and should be distinguished from hypothyroidism, hearing impairment, and dementia. [Walker: 2011]

Ears/Hearing
Hearing loss may be sensorineural, conductive, or mixed in etiology and occur at higher rates in children with Down syndrome. Children 3-5 years old with Down syndrome have a 50-70% risk of chronic serous otitis media. [Bull: 2022] During early development, even minor hearing impairment can negatively impact language and cognitive development - by adulthood, 60-80% have hearing loss.

Sino-pulmonary disease, including recurrent/chronic sinusitis and otitis, occur at higher rates. Children with Down syndrome may also have auditory processing deficits that affect word perception, short-term auditory memory, and sequential auditory memory. The following may be helpful for families: Hearing and Vision Loss Associated with Down Syndrome (TSBVI).

Eyes/Vision
Individuals with Down syndrome are at risk for: [Bull: 2022]

• Nystagmus
• Strabismus
• Cataracts, including congenital and acquired
• Lacrimal duct obstruction
• Refractive errors (50% of children ages 3-5) leading to amblyopia
• Keratoconus (cone-shaped cornea)

All children with Down syndrome should be followed by an ophthalmologist starting at 6 months of age.
Dental
Children and young adults with Down syndrome are at risk for: [Bull: 2022]

• Significant delay in eruption of both primary and secondary teeth
• Missing and/or malformed teeth (hypodontia)
• Dental crowding and overbite
• Periodontal disease, developing in teen years may be rapidly progressive [Bagić: 2003]
• Halitosis
• Cheilosis from chronic oral breathing
• Aphthous ulcers
• Oral candidal infections
• Necrotizing ulcerative gingivitis

Providing preventive dental care may be difficult because:

• Cognitive and fine motor skills may limit the child's ability to perform brushing and flossing.
• Anatomy (small mouth) and oral aversions may make it difficult for others to provide care.
• Behavioral and health issues (e.g., sleep apnea, congenital heart disease) may increase the risk of sedation in the dental setting .
• Abnormalities in the roots of the teeth may impact orthodontic planning.

A helpful handout for parents: Dental Care for the Patient with Down Syndrome.

Endocrine
Thyroid disorders, both congenital and autoimmune hypothyroidism, occur with increased frequency. Congenital hypothyroidism occurs in about 1% of children with Down syndrome. [Bull: 2022] Many children develop euthyroid autoimmune disease, evidenced by a slightly elevated TSH, normal free T4 level, and positive thyroid antibodies. Although opinions vary about if and when to treat this, most endocrinologists do not treat if the child is growing well and the TSH is less than 10-12. These children should be monitored, but it may be many years before they develop a need for medications. Younger children require more frequent monitoring given the impact of hypothyroidism on brain development.

Short stature is common. The current guidelines recommend using standard growth charts rather than Down syndrome charts; however, subsequently updated growth charts for children in the US were published that have improved characteristics. [Zemel: 2015] These updated height, weight, and OFC growth charts are quite useful.

Autoimmune Disorders
The following are associated with Down syndrome:

• Celiac disease (~5%): [Bull: 2022] [Book: 2001] Note that about a third of individuals with Down syndrome and celiac disease have no overt clinical symptoms. [Pavlovic: 2017] See Celiac Disease for more detail.

• 

  Alopecia areata (photo, right): Asymptomatic non-scarring hair loss with spontaneous remissions and exacerbations, often in combination with vitiligo. Alopecia may be localized or may involve the entire scalp or body. Children with alopecia/vitiligo should be carefully evaluated (history and physical) to identify any other associated autoimmune conditions.
• Hashimoto's thyroiditis [Unachak: 2008]
• Diabetes mellitus [Gillespie: 2006]
• Autoimmune hepatobiliary disease (chronic active hepatitis, primary sclerosing cholangitis)
• Autoimmune adrenalitis
• Pernicious anemia
• Vitiligo
• Juvenile idiopathic arthritis [Juj: 2009]

Many other disorders thought to be autoimmune in nature have been reported, including multiple sclerosis, demyelinating neuropathy, and systemic lupus erythematosus. Though more common in adults, these disorders have been reported in children. The mechanisms for autoimmune disease in Down syndrome are poorly understood. They may occur in combination and are more common in patients with certain HLA markers. In childhood, screening is only recommended for thyroid dysfunction and those with symptoms suggestive of celiac disease. However, the clinician should monitor for signs and symptoms of all of these conditions and assess when indicated.

Orthopedics/Skeletal
Hypotonia, ligament laxity, and increased joint flexibility lead to orthopedic concerns. Individuals may also exhibit skeletal differences, such as a thin, weak acetabular capsule, femoral anteversion, and a deficient posterior superior acetabulum that may contribute to orthopedic problems. Orthopedic issues include:

• Spine: Occipitocervical and cervical spine instability (atlanto-axial rotary subluxation, atlanto-occipital instability), scoliosis (7-15%), spondylolisthesis, postural lordosis
• Hip: Up to 8% may have hip problems, including developmental dysplasia of the hip (in this population, hip problems may begin after skeletal maturity and may significantly affect functional ambulation), avascular necrosis, and slipped capital femoral epiphysis.
• Lower leg: Genu valgum, patellar dislocation
• Feet: Planovalgus, metatarsus primus varus, hallux valgus
• Increased risk for low bone density and vitamin D deficiency
• Brachycephaly: though this does not cause functional problems, families may request evaluation by craniofacial specialists to consider molding orthotics
• Atlantoaxial instability: While 13-14% of patients with Down syndrome show evidence of atlantoaxial instability on X-ray, only 1-2% have symptoms that require treatment. Parents should be educated to notify their physician if their child has:
  • Neck pain
  • Persistent head tilt
  • Intermittent or progressive weakness
  • Changes in gait or loss of motor skills
  • Loss of bowel or bladder control
  • Increased or further decreased muscle tone in the legs
  • Changes in sensation in the hands or feet

Dermatologic
Individuals with Down syndrome are at risk for:

• Atopic dermatitis
• Syringomas
• Benign skin tumors arising from sweat glands commonly about the eyes/face
• Norwegian scabies (crusted scabies)
• Xerosis
• Milia-like idiopathic calcinosis cutis
• Skin infections, such as bacterial or fungal folliculitis
• Elastosis perforans serpiginosa: deep red raised lesions often occurring about the neck, chest, and arms
• Angular cheilosis
• Vitiligo

A number of benign dermatologic differences are also described, including:

• Acrocyanosis in the newborn
• Cutis marmorata (may be present up to several months of age in infants with Down syndrome)
• Hyperkeratosis of palms and soles

Urologic
The following conditions have been reported in infants with Down syndrome:

• Renal hypoplasia
• Hydro-uretero-nephrosis
• Uretero-vesical and uretero-pelvic junction obstruction
• Vesico-ureteral reflux
• Posterior urethral valves
• Cryptorchidism
• Testicular cancer
• Infertility (present in most but not all males with Down syndrome)

Developmental
Children with Down syndrome are at increased risk for:

• Delayed gross and fine motor development: Motor delays are secondary to hypotonia, ligamentous laxity, decreased muscle strength, and altered body proportions (shorter arms and legs).
• Social-emotional developmental concerns: Delays in social-emotional development can occur especially in children with Down syndrome who also have an autism spectrum disorder
• Sensory integration concerns: Many children are sensitive to touch, manipulation, and textures in and around their mouth and other parts of their body. Sensory issues may affect oral motor skills, the ability of the parents to care for the child (e.g., dental and facial hygiene, feeding), and the willingness/ability of the child to eat a variety of tastes and textures. Sensory integration issues may be important in expressive communication since producing communicative responses requires processing and integrating sensory input.
• Oral motor impairments: In early development, infants may be at risk for inadequate nutrition due to poor oral motor coordination and low tone. As children mature, additional oral motor problems may include difficulty with different textures, drooling, and verbal apraxia.
• Cognitive concerns: Intellectual disability impacts the majority but not all individuals with Down syndrome. The degree of intellectual disability can vary from mild to profound. Additional cognitive processing concerns are common although often hard to define (e.g., slow processing, working memory deficits, challenges with understanding sequences).
• Executive function problems: Can present as symptoms consistent with ADHD, a common comorbid condition

Current & Past Medical History

Document past and present comorbid conditions, including prior evaluative (e.g., cardiac echo, swallow study, sleep study) and surgical procedures. A full review of symptoms is helpful, given the myriad comorbid conditions associated with Down syndrome. Of particular concern are cardiorespiratory, sleep, feeding, gastrointestinal symptoms, learning/behavior, signs or symptoms of myelopathy, and concerns regarding hearing and vision.

Family History

A 3-generation pedigree is indicated, though a family history of Down syndrome or another chromosome abnormality is unlikely. The incidence of aneuploidy in offspring increases with parental age, particularly maternal age. A family history of pregnancy loss, especially miscarriages, can suggest a familial translocation.

Pregnancy/Perinatal History

The pregnancy and perinatal history may include:

• Abnormal prenatal ultrasounds (e.g., polyhydramnios, suggesting duodenal obstruction, or minor ultrasound findings, such as redundant nuchal skin and increased nuchal translucency)
• Abnormal first- and second-trimester maternal screening (including confirmation of diagnosis by amniocentesis or chorionic villus sampling in some patients)
• Detection of structural defects (including the prenatal diagnosis by ultrasound of cardiovascular malformations or duodenal atresia)

Developmental & Educational Progress

The child's functional abilities are key to management. Assess the child’s method and level of expressive communication and his/her understanding of language. Many children with Down syndrome have significantly higher receptive than expressive language abilities, which is sometimes related to verbal apraxia or ASD. Typical Down syndrome language milestones include:

• Smiling by 2 months (SD 1.5-4 months)
• Verbalizing single words by 16 months (SD 9-31 months)
• Verbalizing early phrases by 28 months (SD 19-96 months)

Average ages for attainment of gross motor skills in Down syndrome include:

• Rolling stomach to back by 6 months
• Rolling back to stomach by 7 months
• Sitting independently at 11 months
• Belly crawl (>5 ft) by 14 months
• Pull to stand from hands and feet by 17 months
• Independent standing (>10 sec) by 21 months
• Walking (15-20 ft) by 26 months

There is wide variation around these averages, and the child with ongoing medical issues (e.g., repeated illness or surgeries) may exhibit further delays. However, it is a pitfall to blame excessive delays on medical issues without carefully considering the potential for comorbid conditions such as hearing loss or autism. Review the services the child receives through early intervention, the school district, or private therapy providers, the child's rate of progress, and parents' satisfaction with current services.
Inquire about family, teacher, therapist, and other caregiver concerns regarding development, attainment of functional goals, ADHD or ASD symptoms, and/or behavioral challenges. Skills in activities of daily living, eating, and community integration should be discussed with goals set for each.

Behavior challenges are common, including sleep and feeding concerns, internalizing/externalizing behaviors, and poor social inclusion. Consider whether problem behaviors and their frequency and intensity are consistent with the child's functional abilities. The 5-year-old whose receptive language skills are at the 3-year level is likely to have temper tantrums, a relatively short attention span, some oppositional behavior, and aggression. Prolonged temper tantrums, extreme irritability, or pervasive oppositional behavior would not be expected; additional evaluation and behavioral supports would be indicated. Determine how these behaviors affect family functioning and what supports the family has to manage them.

Maturational Progress

Pubertal development should be expected within the same age parameters as for children without Down syndrome.

Social & Family Functioning

The understanding of Down syndrome by parents, siblings, and extended family members and their adaptation to the child's special needs should be discussed. When you meet with a family whose child has just been diagnosed, asking family members if they have known someone with Down syndrome often uncovers preconceived notions about outcomes. Ask about awareness of community resources for health care funding (e.g., Medicaid and relevant waivers, caveats of private insurance, including benefit exclusions and mechanisms to advocate for appropriate funding), financial supports (e.g., SSI and role of Workforce Services), services to optimize development and function (e.g., early intervention, developmental preschool, special education, inclusion models, private therapies, augmented communication supports), respite, appropriate recreational/social outlets, and transition (e.g., vocational rehabilitation, guardianship association). Discuss potential value of one-time or intermittent family medical leave (FMLA) for the parents. .

Current functional goals, intervention supports, and adaptive equipment should be reviewed to identify gaps in needed support. Ensure families have access to information on life and financial planning for their child. Families should understand the role of a special needs trust to protect funds put aside to support their child in adulthood; otherwise, they will need to spend down those funds to obtain/retain Medicaid or SSI funding. Include the child in these discussions at a developmentally appropriate level. Pubertal development, self-exploration, menstrual hygiene, and sexuality should be discussed as the child approaches adolescence.

At all ages, ask about safety concerns, such as taking off in parking lots (consider a DMV form for a disability parking pass), refusing to wear a seat belt (consider an adapted car seat), and wandering (consider a tracking device and safety measures to prevent opening the house doors). Discuss approaches to prevent sexual victimization (e.g., discussing at the child’s level appropriate/inappropriate touch, teaching normal sexual function if appropriate for the teens cognitive level, encouraging parents to ensure all programs the child participates in have policies on prevention, and having family members treat the teen with appropriate body space behaviors for age).

Physical Exam

Sensory Testing

Vision
Following a normal routine newborn examination, the AAP counsels consideration of referral to an ophthalmologist within the 6 months of life. [Bull: 2022] Follow-up with a pediatric ophthalmologist, or general ophthalmologist familiar with Down syndrome, should occur annually for 1- to 5-year-olds, every 2 years for 6- to 13-year-olds, and every 3 years for 14- to 21-year-olds.

Hearing
In addition to assessment by history at every well-child visit, AAP guidelines suggest: [Bull: 2022]

• Test by an objective method (e.g., otoacoustic emissions, brainstem auditory evoked response) at birth.
• Repeat assessment "by objective method" or behavioral screening plus tympanometry every 6 months until normal ear-specific hearing is confirmed (usually around age 4).
• Attempt first behavioral audiogram by 1 year and repeat annually after normal ear-specific hearing is confirmed.
• Objective hearing assessment should be repeated whenever there is parental concern or evidence of persistent middle ear effusions.
• Tympanometry may be helpful in the cooperative child to detect normal motility or presence of effusions.

Laboratory Testing

AAP screening guidelines recommend: [Bull: 2022]

• Thyroi-stimulating hormone (TSH) at newborn screen, 6 months, and annually. Check additional thyroid function tests if the TSH is abnormal. Some experts recommend measuring thyroxine level (free T4) or thyroid antibodies routinely along with TSH screen; however, there is no consensus among international guidelines. In the event of a mildly elevated TSH, obtain a free T4 (to determine need for treatment) and measurement of thyroid antibodies may help to identify those with evolving autoimmune thyroid disease; however, only a minority will progress to hypothyroidism, and no consensus exists on the need to treat subclinical hypothyroidism.
• Celiac testing (e.g., celiac reflexive panel, which guides testing based upon age and serum IgA level for optimal sensitivity) if any suggestive symptoms. While there is lack of expert consensus on whether to routinely screen children with Down syndrome for celiac disease, the AAP recommends screening for symptoms that may be related to celiac disease in children with Down syndrome at yearly visits and perform serologic screening if symptoms are present. Some expert groups now recommend one-time testing of HLA-DQ2 and HLA-DQ8 to help exclude those individuals who are not at risk for celiac disease. [Bull: 2022] [Pavlovic: 2017]
• Complete blood count with differential in the newborn period to screen for myeloproliferative disorder and polycythemia. Monitoring for resolution of the myeloproliferation (and continued intermittent monitoring until 3 years of age even after resolution) with a CBC is indicated in children who have had transient myeloproliferation.
• Hemoglobin annually. Guidelines recommend yearly monitoring of hemoglobin and historically asking about risk factors of iron deficiency. Screen with a CRP/ferritin (or reticulocyte hemoglobin) yearly if there are any risk factors for iron deficiency or if the hemoglobin is <11.

Imaging

• An echocardiogram should be performed on every newborn with Down syndrome to exclude a cardiac defect. In children diagnosed with obstructive sleep apnea, evaluation with an echocardiogram may be indicated on an intermittent basis to assess for pulmonary hypertension. Echocardiographic screening has been recommended in the AAP treatment guidelines for ages 13-21 if "there is a history of increasing fatigue, shortness of breath, or exertional dyspnea or abnormal physical exam findings, such as a new murmur or gallop." [Bull: 2022]
• Consider a KUB in any newborn with Down syndrome if there is concern for duodenal atresia (double-bubble sign). Additional assessment with upper gastrointestinal series (upper GI) and/or barium enema should be considered to assess anatomy in infants with gastrointestinal symptoms.
• Obtain an "unprepped" barium enema for any concern for Hirschsprung disease.
• Neuroimaging is not routinely indicated but should be considered in a child with macrocephaly or severe microcephaly beyond that typically observed in Down syndrome, a child whose development seems atypical for Down syndrome, any child with seizures or a change in neurologic functioning or developmental regression, and a child who has abnormalities on neurologic examination that cannot be attributed to Down syndrome.
• The AAP guidelines do not recommend universal screening of infants with Down syndrome for renal and urologic abnormalities. However, any child with Down syndrome and urinary symptoms (e.g., UTI, difficulty with voiding, unexplained enuresis) should have an evaluation of the urinary tract.
• Although not all sports programs have caught up with this recommendation, the AAP guidelines do not recommend screening for upper cervical spine instability unless symptomatic. The normal atlas-dens interval is less than 3.5 mm in children but may normally reach 5 mm in children with Down syndrome. If signs or symptoms of atlantoaxial instability emerge, evaluation should proceed with c-spine x-rays (neutral position followed by flexion/extension only if no abnormality is seen), neuroimaging, and consultation with neurosurgeon or orthopedic surgeon with expertise.

Genetic Testing

Newborns can be screened for trisomy 21 with a fluorescent in situ hybridization (FISH) test when there is clinical suspicion. If the FISH screen is positive, it should be confirmed with a complete karyotype. [Bull: 2022] In utero diagnostic testing with CVS or amniocentesis nears 100% accuracy and distinguishes among the genetic types of Down syndrome: trisomy 21, translocation, and mosaicism. If a screen or cell free DNA during gestation was abnormal but in utero diagnostic testing was not completed, a karyotype should be completed in the newborn period to confirm the diagnosis and genetic etiology. If cytogenomic microarray (CMA) is performed in the prenatal or newborn period, a karyotype needs to be performed as well because CMA does not distinguish the standard trisomy 21 from the translocation type.

• Fluorescent in situ hybridization (FISH) testing usually takes 1-4 days; results are not diagnostic. [Bull: 2022]
• A karyotype performed on lymphocytes confirms the diagnosis and genetic type. e. [Bull: 2022] Karyotypes may take 10 or more days.
• Genetic studies should be subsequently offered to the parents only when the child has a translocation. Prenatal diagnosis in future pregnancies, either with chorionic villous sampling at 10-13 weeks or amniocentesis at 15-20 weeks, is usually offered. Preimplantation testing is also available to screen blastomeres for aneuploidy and translocations, but the cost is substantial since this process requires in vitro fertilization and ICSI (intracytoplasmic sperm injection).
• It is critical for the clinician to understand that genetic testing is expensive and not all insurances will cover it. Some insurances will not approve a karyotype if the child had a positive cell-free DNA in utero or a positive FISH. This is because, if clinically the child has Down syndrome, they do not consider knowing if it is a translocation or mosaic medically necessary (it does not change treatment, recurrence risk assessment is medically indicated for the parents but not the child). In general, no testing should be sent without prior authorization. This is particularly true on the outpatient side, but insurances will sometimes deny testing sent inpatient, too.

Other Testing

Sleep Study
Obtain a sleep study by age 4 or sooner if any symptoms of sleep apnea or other non-behavioral sleep problems are noted, such as restless legs.

Modified Barium Swallow (MBSS)
Guidelines recommend evaluating for aspiration with an MBSS in any infant with suggestive symptoms, including marked hypotonia, slow feeding, choking, recurrent/persistent respiratory symptoms, or failure to thrive. This will be particularly helpful if a speech and language pathologist is present during the study to assess and make recommendations.

Electroencephalogram (EEG)
An EEG can be obtained if there are concerns for seizures.

Overview

Since there is no treatment for the underlying genetic abnormality in Down syndrome, treatment focuses on managing comorbid conditions and optimizing function and societal participation.

Pearls & Alerts for Treatment & Management

Respiratory infections can cause hospitalization after NICU discharge

Respiratory infections, such as pneumonia and bronchiolitis, are second only to congenital heart disease as causes for hospitalizations and are associated with increased morbidity and mortality compared to other children hospitalized for the same infections.

Altitude and pulmonary edema

A case series that included 6 children with Down syndrome reported high-altitude pulmonary edema. after traveling to moderate altitudes (1738-3252 feet) for a short time (several in under 24 hours). [Durmowicz: 2001] Among the 6 children, 4 had congenital heart defects, 3 had chronic pulmonary hypertension, and 5 had developed an intercurrent illness just before their travel. The author suggested care when traveling to even moderate altitudes with children with Down syndrome. Other authors have suggested an increased risk for those with obstructive sleep apnea perhaps related to altered chemo responsiveness to hypoxia. [Richalet: 2008]

Atlantoaxial instability

New onset of focal weakness or bowel/bladder incontinence merits urgent neurosurgical consultation. More of my time is spent these days explaining why x-rays are not needed to screen, helping them know the signs to watch for (and that these are rare but important to take seriously), and encouraging them to have their child participate in sports avoiding the very few activities that guidelines suggest restricting (head first diving, trained tumbling (toddlers are going to do it and stopping them just wants to make them do it more), rugby, trampoline before 6 years of age and after that ensure supervision).

Polycythemia and sleep apnea

Increased red blood cells may be noted in the setting of chronic sleep apnea or chronically inadequate fluid intake.

Psychoactive medications

Many children with neurodevelopmental disorders are sensitive to psychoactive medications. Use very low doses (e.g., half the starting dose for a neurotypical child) when starting medications, such as SSRIs, and titrate slowly to avoid activation and other side effects. Having said that, many children with Down syndrome benefit from careful management of mental health issues with medications such as stimulants for ADHD, SSRIs for depression or anxiety, and mood stabilizers for self-injury in the face of ASD. Review with families carefully potential side effects (e.g., agitation, insomnia) and targeted symptoms (e.g., anxiety, impulsivity, depression symptoms).

Anticipatory well care

Safety and toilet training (often as part of the child’s IEP) are often overlooked in the fray of the child’s medical needs, but they are critical to include in the child’s preventive care discussions.

Growth or Weight Gain

The most current guidance is to use a standard growth chart complemented by the Down syndrome growth charts published in 2015 (and not the widely distributed Down syndrome growth charts previously published).

Development (Cognitive, Motor, Language, Social-Emotional)

Be aware that some children with Down syndrome may also have autism spectrum disorder (ASD). A specialist should perform formal evaluation for an ASD in the context of Down syndrome. Evaluation can be helpful in accessing services specific to treatment of ASD, such as Applied Behavior Analysis (ABA therapy). See Autism Spectrum Disorder for more details.

Viral Infections

Children with Down syndrome can have significant morbidity from viral respiratory infections, particularly in the face of a heart defect, pulmonary hypertension, severe LTM, or significant sleep obstruction. Some children may qualify for Synagis to reduce the risk of RSV infection; based on age and comorbidities, influenza vaccination should be encouraged. Many children have had recurrent croup, and proactive provision of single-dose steroids can be helpful.

Bacterial Infections

Due to narrow ear canals, it can be challenging to visualize the tympanic membranes. Sometimes, given the clinical scenario (e.g., the child has had a URI for a number of days and suddenly becomes febrile and sleeping poorly), the clinician suspects but cannot tell and may have to make a judgment call. Over time, work with an ootolaryngologist to determine if persistent effusions are present and to place tubes for recurrent middle ear infections. Children with Down syndrome have an increased prevalence of sinusitis. Many children with Down syndrome will benefit from a Pneumovax vaccination at age 2 years based upon comorbidities.

Other

Many children with Down syndrome have significant oral sensory symptoms. Consideration of this when prescribing oral medications (e.g., pill crushed vs. liquid vs. sprinkles, compounding for taste) may help with compliance.

Systems

On the Web

Council on Genetics (AAP)
Supports the integration of genetic and genomic medicine in pediatric health care by expanding the genetic literacy of pediatric teams and supporting the professional needs of geneticists; American Academy of Pediatrics.

Trisomy 21 (OMIM)
Information about clinical features, diagnosis, management, and molecular and population genetics; Online Mendelian Inheritance in Man, authored and edited at the McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine

Helpful Articles

PubMed search for Down syndrome in children or adolescents, last year

Baumer N, Davidson EJ.
Supporting a happy, healthy adolescence for young people with Down syndrome and other intellectual disabilities: recommendations for clinicians.
Curr Opin Pediatr. 2014;26(4):428-34. PubMed abstract

Bull MJ.
Down Syndrome.
N Engl J Med. 2020;382(24):2344-2352. PubMed abstract

Korlimarla A, Hart SJ, Spridigliozzi GA, Kishnani PS.
Cassidy and Allanson’s Management of Genetic Syndromes.
4 ed. Hoboken, NJ: John Wiley & Sons; 2021.

Skotko BG, Capone GT, Kishnani PS.
Postnatal diagnosis of Down syndrome: synthesis of the evidence on how best to deliver the news.
Pediatrics. 2009;124(4):e751-8. PubMed abstract

Watts R, Vyas H.
An overview of respiratory problems in children with Down's syndrome.
Arch Dis Child. 2013;98(10):812-7. PubMed abstract

Clinical Checklists & Visit Tools

Down Syndrome Checklist (2022) ( 487 KB)
A checklist for recommended monitoring and screening of children with Down syndrome, from the AAP Clinical Report by Bull et al. (PEDIATRICS Volume 149, number 5, May 2022)

Growth/BMI Charts

Down Syndrome Growth Charts (CDC)
Growth charts used on over 1500 measurements on 637 individual with DS, published by Zemel, et al. in 2015, from the Centers for Disease Control and Prevention's site.

Patient Education & Instructions

Children with Down Syndrome: Health Care Information for Families (AAP)
Comprehensive guide to help parents and families of children with Down syndrome. Focuses on medical topics, by age, that affect physical health. Includes links to health care information for families of children with Down syndrome. PDF downloads available; American Academy of Pediatrics.

Living with Down Syndrome (Down Syndrome Educational Trust) ( 951 KB)
A 26-page, printable booklet with information about family, school, social, and medical issues particular to those with Down syndrome. It has a positive focus and includes personal stories and helpful advice for parents and families.

A Parent's Guide to Puberty for Children with Disabilities (LEND) ( 7 KB)
Toolkits for parents to help adolescents with disabilities learn about puberty, personal hygiene, acceptable public behavior, and peer relations. Offers versions for girls and boys with disabilities and some translations; Vanderbilt Leadership Education in Neurodevelopmental Disabilities.

Toilet Training Children with Down Syndrome (National Down Syndrome Society)
A guide to help determine toileting readiness and teach toileting skills to children with developmental disabilities. Includes simple images that may be used as visual cues.

Information on the Web

Down Syndrome (MedlinePlus)
Excellent, detailed review of condition for patients and families; National Library of Medicine and National Institutes of Health.

Atlantoaxial Instability in Children with Down Syndrome (HealthyChildren.org)
Warning signs for compression of the spinal cord called atlantoaxial instability; American Academy of Pediatrics.

Down Syndrome - Health Issues
Site developed and edited/authored by a pediatrician, Len Leshin, MD, who has a son with Down syndrome. Includes a number of essays by experts about specific health topics and provides other useful links.

Down Syndrome Misconceptions vs. Reality (Global Down Syndrome Foundation)
The reality of misconceptions about Down syndrome.

The International Mosaic Down Syndrome Association
Aims to assist any family or individual whose life has been affected by mosaic Down syndrome; includes a helpful list of frequently asked questions.

What is Down Syndrome (National Down Syndrome Society )
An in-depth look at Down syndrome with information for children and adults, which provides a good explanation of the condition and useful information.

Sexuality and People with Disabilities ( 257 KB)
This Medical Home newsletter provides information for primary care providers and families including Sexuality and People with Disabilities; American Academy of Pediatrics recommendations for education about sexuality; tips for parents; and resources, books, and websites for parents and providers.

Hearing and Vision Loss Associated with Down Syndrome (TSBVI)
An overview for families; Texas School for the Blind and Visually Impaired.

Dental Care for the Patient with Down Syndrome
Topics covered: Medical problems associated with Down syndrome that can affect dental treatment; proper home care and prevention of dental disease; techniques to help children with Down syndrome become cooperative dental patients; choosing the right dentist; and how to communicate effectively with the dental staff. by Dr. Elizabeth S. Pilcher, 1997, but still relevant.

Down Syndrome - Autism Connection
Organization focused on providing education, support, and resources related to the unique challenges caused by co-occurring Down syndrome and autism.

National & Local Support

National Down Syndrome Congress
The NDSC, a membership organization, offers parent resources, including a "new parent package" of information, resources for adult siblings caring for a loved one, and information for people with Down syndrome themselves.

Down Syndrome - Autism Connection
Organization focused on providing education, support, and resources related to the unique challenges caused by co-occurring Down syndrome and autism.

National Down Syndrome Society (NDSS)
Human rights organization for all individuals with Down syndrome that focuses on 3 key areas of programming: Resources & Support, Policy & Advocacy, and Community Engagement.

Studies/Registries

Clinical Trials in Children with Down Syndrome (clinicaltrials.gov)
Studies looking at better understanding, diagnosing, and treating this condition; from the National Library of Medicine.

DS-Connect: The Down Syndrome Registry (NIH)
This site offers patients and families opportunities to connect with researchers and health care providers, and access research data. Patients and families can take confidential health-related surveys and express interest in participating in clinical studies on Down syndrome. Developed by the Down Syndrome Consortium, led by the National Institutes of Health and involving several Down syndrome advocacy and professional organizations.

Services for Patients & Families in Nevada (NV)

Service Categories	# of providers* in:	NV	NW	Other states (4)  (show)		NM	OH	RI	UT
Adaptive Sports		21	10		22	10	28	59
Audiology		8	3		19	4	25	28
Autism Programs		2			5		3	58
Bone Densitometry/DEXA
Breastfeeding Support & Equipment		12	6		6	7	16	26
Dental Care Expense Assistance		3			1	1	4	3
Developmental - Behavioral Pediatrics		2	1		2	2	12	9
Developmental Assessments		6	1		104	1	35	56
Early Intervention for Children with Disabilities/Delays		32	3		35	3	14	55
General Counseling Services		209	1		3	1	30	362
General Dentistry		25	1		8	1	34	105
Gynecology: Pediatric/Adolescent; Special Needs						1	3	13
Medical Genetics		5	1		2	1	4	8
Neuropsychiatry/Neuropsychology		5			1		9	9
Nutrition Assessment Services		3				1	2	6
Occupational Therapy		27	1		17	2	19	38
Orthodontics		4					3	20
Outpatient Mental Health Care		45			20		16	239
Pediatric Cardiology		4			2		17	5
Pediatric Dentistry		31	2		6	3	41	50
Pediatric Dermatology		1	1		3	1	3	2
Pediatric Endocrinology		6	1		4	1	13	4
Pediatric Gastroenterology		6	1		3	1	19	4
Pediatric Immunology		1			3		6	6
Pediatric Infectious Disease		2			2		4	1
Pediatric Neurology		5			5		17	6
Pediatric Neurosurgery		4	1		2	1	3	2
Pediatric Ophthalmology		6	1		6	1	8	4
Pediatric Orthopedics		8	4		6	4	16	21
Pediatric Otolaryngology (ENT)		5	1		8	1	7	10
Pediatric Pulmonology		4			4		8	5
Pediatric Rheumatology		2	1		2	1	2	3
Pediatric Urology		13					1	3
Physical Therapy		11			12	1	5	48
Psychiatry/Medication Management		49			2		79	56
Sleep Disorders							2	4
Special Education/Schools		9	3		82	4	40	44
Speech - Language Pathologists		13	4		22	4	31	69

For services not listed above, browse our Services categories or search our database.

* number of provider listings may vary by how states categorize services, whether providers are listed by organization or individual, how services are organized in the state, and other factors; Nationwide (NW) providers are generally limited to web-based services, provider locator services, and organizations that serve children from across the nation.

Alexander M, Ding Y, Foskett N, Petri H, Wandel C, Khwaja O.
Population prevalence of Down's syndrome in the United Kingdom.
J Intellect Disabil Res. 2016;60(9):874-8. PubMed abstract

American College of Obstetricians and Gynecologists’ Committee on Practice Bulletins—Obstetrics; Committee on Genetics; Society for Maternal–Fetal Medicine.
Practice Bulletin No. 162: Prenatal Diagnostic Testing for Genetic Disorders.
Obstet Gynecol. 2016;127(5):e108-22. PubMed abstract

Aumonier ME, Cunningham CC.
Breast feeding in infants with Down's syndrome.
Child Care Health Dev. 1983;9(5):247-55. PubMed abstract

Badeau M, Lindsay C, Blais J, Nshimyumukiza L, Takwoingi Y, Langlois S, Légaré F, Giguère Y, Turgeon AF, Witteman W, Rousseau F.
Genomics-based non-invasive prenatal testing for detection of fetal chromosomal aneuploidy in pregnant women.
Cochrane Database Syst Rev. 2017;11:CD011767. PubMed abstract / Full Text

Bagić I, Verzak Z, Cuković-Cavka S, Brkić H, Susić M.
Periodontal conditions in individuals with Down's syndrome.
Coll Antropol. 2003;27 Suppl 2:75-82. PubMed abstract

Barca D, Tarta-Arsene O, Dica A, Iliescu C, Budisteanu M, Motoescu C, Butoianu N, Craiu D.
Intellectual disability and epilepsy in down syndrome.
Maedica (Buchar). 2014;9(4):344-50. PubMed abstract / Full Text

Baumer N, Davidson EJ.
Supporting a happy, healthy adolescence for young people with Down syndrome and other intellectual disabilities: recommendations for clinicians.
Curr Opin Pediatr. 2014;26(4):428-34. PubMed abstract

Bertapelli F, Pitetti K, Agiovlasitis S, Guerra-Junior G.
Overweight and obesity in children and adolescents with Down syndrome-prevalence, determinants, consequences, and interventions: A literature review.
Res Dev Disabil. 2016;57:181-92. PubMed abstract

Bocian AB, Wasserman RC, Slora EJ, Kessel D, Miller RS.
Size and age-sex distribution of pediatric practice: a study from Pediatric Research in Office Settings.
Arch Pediatr Adolesc Med. 1999;153(1):9-14. PubMed abstract

Book L, Hart A, Black J, Feolo M, Zone JJ, Neuhausen SL.
Prevalence and clinical characteristics of celiac disease in Downs syndrome in a US study.
Am J Med Genet. 2001;98(1):70-4. PubMed abstract

Boëchat MC, Silva KS, Llerena JC Jr, Boëchat PR.
Cholelithiasis and biliary sludge in Downs syndrome patients.
Sao Paulo Med J. 2007;125(6):329-32. PubMed abstract

Brouillette RT, Manoukian JJ, Ducharme FM, Oudjhane K, Earle LG, Ladan S, Morielli A.
Efficacy of fluticasone nasal spray for pediatric obstructive sleep apnea.
J Pediatr. 2001;138(6):838-44. PubMed abstract

Bull MJ.
Down Syndrome.
N Engl J Med. 2020;382(24):2344-2352. PubMed abstract

Bull MJ, Trotter T, Santoro SL, Christensen C, Grout RW, Burke LW, Berry SA, Geleske TA, Holm I, Hopkin RJ, Introne WJ, Lyons MJ, Monteil DC, Scheuerle A, Stoler JM, Vergano SA, Chen E, Hamid R, Downs SM, Grout RW, Cunniff C, Parisi MA, Ralston SJ, Scott JA, Shapira SK, Spire P.
Health Supervision for Children and Adolescents With Down Syndrome.
Pediatrics. 2022;149(5). PubMed abstract / Full Text

Caird MS, Wills BP, Dormans JP.
Down syndrome in children: the role of the orthopaedic surgeon.
J Am Acad Orthop Surg. 2006;14(11):610-9. PubMed abstract

Capone G, Goyal P, Ares W, Lannigan E.
Neurobehavioral disorders in children, adolescents, and young adults with Down syndrome.
Am J Med Genet C Semin Med Genet. 2006;142C(3):158-72. PubMed abstract

Capone GT, Brecher L, Bay M.
Guanfacine Use in Children With Down Syndrome and Comorbid Attention-Deficit Hyperactivity Disorder (ADHD) With Disruptive Behaviors.
J Child Neurol. 2016;31(8):957-64. PubMed abstract

Capone GT, Goyal P, Grados M, Smith B, Kammann H.
Risperidone use in children with Down syndrome, severe intellectual disability, and comorbid autistic spectrum disorders: a naturalistic study.
J Dev Behav Pediatr. 2008;29(2):106-16. PubMed abstract

Committee on Practice Bulletins—Obstetrics, Committee on Genetics, and the Society for Maternal-Fetal Medicine.
Practice Bulletin No. 163: Screening for Fetal Aneuploidy.
Obstet Gynecol. 2016;127(5):e123-37. PubMed abstract

Committee on Practice and Ambulatory Medicine, Bright Futures Periodicity Schedule Workgroup.
2017 Recommendations for preventive pediatric health care.
Pediatrics. 2017;139(4). PubMed abstract / Full Text
Includes a link to the Periodicity Schedule, https://www.aap.org/en-us/Documents/periodicity_schedule.pdf.

Crisafulli G, Aversa T, Zirilli G, Pajno GB, Corica D, De Luca F, Wasniewska M.
Subclinical Hypothyroidism in Children: When a Replacement Hormonal Treatment Might Be Advisable.
Front Endocrinol (Lausanne). 2019;10:109. PubMed abstract / Full Text

Dixon N, Kishnani PS, Zimmerman S.
Clinical manifestations of hematologic and oncologic disorders in patients with Down syndrome.
Am J Med Genet C Semin Med Genet. 2006;142C(3):149-57. PubMed abstract

Dixon NE, Crissman BG, Smith PB, Zimmerman SA, Worley G, Kishnani PS.
Prevalence of iron deficiency in children with Down syndrome.
J Pediatr. 2010;157(6):967-971.e1. PubMed abstract / Full Text

Downes A, Anixt JS, Esbensen AJ, Wiley S, Meinzen-Derr J.
Psychotropic Medication Use in Children and Adolescents With Down Syndrome.
J Dev Behav Pediatr. 2015;36(8):613-9. PubMed abstract

Durmowicz AG.
Pulmonary edema in 6 children with Down syndrome during travel to moderate altitudes.
Pediatrics. 2001;108(2):443-7. PubMed abstract
of particular relevance perhaps in Utah.

Dykens EM.
Psychiatric and behavioral disorders in persons with Down syndrome.
Ment Retard Dev Disabil Res Rev. 2007;13(3):272-8. PubMed abstract

Farhood Z, Isley JW, Ong AA, Nguyen SA, Camilon TJ, LaRosa AC, White DR.
Adenotonsillectomy outcomes in patients with Down syndrome and obstructive sleep apnea.
Laryngoscope. 2017;127(6):1465-1470. PubMed abstract

Ghaziuddin N, Nassiri A, Miles JH.
Catatonia in Down syndrome; a treatable cause of regression.
Neuropsychiatr Dis Treat. 2015;11:941-9. PubMed abstract / Full Text

Gillespie KM, Dix RJ, Williams AJ, Newton R, Robinson ZF, Bingley PJ, Gale EA, Shield JP.
Islet autoimmunity in children with Down's syndrome.
Diabetes. 2006;55(11):3185-8. PubMed abstract

Ieiri S, Higashi M, Teshiba R, Saeki I, Esumi G, Akiyoshi J, Nakatsuji T, Taguchi T.
Clinical features of Hirschsprung's disease associated with Down syndrome: a 30-year retrospective nationwide survey in Japan.
J Pediatr Surg. 2009;44(12):2347-51. PubMed abstract

Jackson JM, Crider KS, Cragan JD, Rasmussen SA, Olney RS.
Frequency of prenatal cytogenetic diagnosis and pregnancy outcomes by maternal race-ethnicity, and the effect on the prevalence of trisomy 21, Metropolitan Atlanta, 1996-2005.
Am J Med Genet A. 2014;164A(1):70-6. PubMed abstract / Full Text

Juj H, Emery H.
The arthropathy of Down syndrome: an underdiagnosed and under-recognized condition.
J Pediatr. 2009;154(2):234-8. PubMed abstract

Keeling LA, Spiridigliozzi GA, Hart SJ, Baker JA, Jones HN, Kishnani PS.
Challenges in measuring the effects of pharmacological interventions on cognitive and adaptive functioning in individuals with Down syndrome: A systematic review.
Am J Med Genet A. 2017;173(11):3058-3066. PubMed abstract

Korlimarla A, Hart SJ, Spridigliozzi GA, Kishnani PS.
Cassidy and Allanson’s Management of Genetic Syndromes.
4 ed. Hoboken, NJ: John Wiley & Sons; 2021.

La Francis ME.
A chiropractic perspective on atlantoaxial instability in Down's syndrome.
J Manipulative Physiol Ther. 1990;13(3):157-60. PubMed abstract

Lin AE, Basson CT, Goldmuntz E, Magoulas PL, McDermott DA, McDonald-McGinn DM, McPherson E, Morris CA, Noonan J, Nowak C, Pierpont ME, Pyeritz RE, Rope AF, Zackai E, Pober BR.
Adults with genetic syndromes and cardiovascular abnormalities: clinical history and management.
Genet Med. 2008;10(7):469-94. PubMed abstract / Full Text

Lott IT.
Neurological phenotypes for Down syndrome across the life span.
Prog Brain Res. 2012;197:101-21. PubMed abstract / Full Text

Macchini F, Leva E, Torricelli M, Valadè A.
Treating acid reflux disease in patients with Down syndrome: pharmacological and physiological approaches.
Clin Exp Gastroenterol. 2011;4:19-22. PubMed abstract / Full Text

Mai CT, Kucik JE, Isenburg J, Feldkamp ML, Marengo LK, Bugenske EM, Thorpe PG, Jackson JM, Correa A, Rickard R, Alverson CJ, Kirby RS.
Selected birth defects data from population-based birth defects surveillance programs in the United States, 2006 to 2010: featuring trisomy conditions.
Birth Defects Res A Clin Mol Teratol. 2013;97(11):709-25. PubMed abstract / Full Text

Menéndez M.
Down syndrome, Alzheimer's disease and seizures.
Brain Dev. 2005;27(4):246-52. PubMed abstract

Mik G, Gholve PA, Scher DM, Widmann RF, Green DW.
Down syndrome: orthopedic issues.
Curr Opin Pediatr. 2008;20(1):30-6. PubMed abstract

Miles JH, Takahashi N, Muckerman J, Nowell KP, Ithman M.
Catatonia in Down syndrome: systematic approach to diagnosis, treatment and outcome assessment based on a case series of seven patients.
Neuropsychiatr Dis Treat. 2019;15:2723-2741. PubMed abstract / Full Text

Moore SW.
Down syndrome and the enteric nervous system.
Pediatr Surg Int. 2008;24(8):873-83. PubMed abstract

Morris JK, Alberman E.
Trends in Down's syndrome live births and antenatal diagnoses in England and Wales from 1989 to 2008: analysis of data from the National Down Syndrome Cytogenetic Register.
BMJ. 2009;339:b3794. PubMed abstract / Full Text

Murillo-Vallés M, Martinez S, Aguilar-Riera C, Garcia-Martin MA, Bel-Comós J, Ybern MLG.
Subclinical hypothyroidism in childhood, treatment or only follow-up?.
BMC Pediatr. 2020;20(1):282. PubMed abstract / Full Text

Murphy NA, Elias ER.
Sexuality of children and adolescents with developmental disabilities.
Pediatrics. 2006;118(1):398-403. PubMed abstract / Full Text
This American Academy of Pediatrics' Clinical Report provides additional information and guidance for providers relating to puberty, psychosocial considerations, sexual abuse, sexuality education, and the pediatrician's role.

Nation J, Brigger M.
The Efficacy of Adenotonsillectomy for Obstructive Sleep Apnea in Children with Down Syndrome: A Systematic Review.
Otolaryngol Head Neck Surg. 2017;157(3):401-408. PubMed abstract

Natoli JL, Ackerman DL, McDermott S, Edwards JG.
Prenatal diagnosis of Down syndrome: a systematic review of termination rates (1995-2011).
Prenat Diagn. 2012;32(2):142-53. PubMed abstract

Oxelgren UW, Myrelid Å, Annerén G, Ekstam B, Göransson C, Holmbom A, Isaksson A, Åberg M, Gustafsson J, Fernell E.
Prevalence of autism and attention-deficit-hyperactivity disorder in Down syndrome: a population-based study.
Dev Med Child Neurol. 2017;59(3):276-283. PubMed abstract

Pavlovic M, Berenji K, Bukurov M.
Screening of celiac disease in Down syndrome - Old and new dilemmas.
World J Clin Cases. 2017;5(7):264-269. PubMed abstract / Full Text

Plaiasu V.
Down Syndrome - Genetics and Cardiogenetics.
Maedica (Buchar). 2017;12(3):208-213. PubMed abstract / Full Text

Richalet JP, Chenivesse C, Larmignat P, Meille L.
High altitude pulmonary edema, down syndrome, and obstructive sleep apneas.
High Alt Med Biol. 2008;9(2):179-81. PubMed abstract

Skotko BG, Capone GT, Kishnani PS.
Postnatal diagnosis of Down syndrome: synthesis of the evidence on how best to deliver the news.
Pediatrics. 2009;124(4):e751-8. PubMed abstract

Skotko BG, Kishnani PS, Capone GT.
Prenatal diagnosis of Down syndrome: how best to deliver the news.
Am J Med Genet A. 2009;149A(11):2361-7. PubMed abstract

Taşdemir HA, Cetinkaya MC, Polat C, Belet U, Kalayci AG, Akbaş S.
Gallbladder motility in children with Down syndrome.
J Pediatr Gastroenterol Nutr. 2004;39(2):187-91. PubMed abstract

Unachak K, Tanpaiboon P, Pongprot Y, Sittivangkul R, Silvilairat S, Dejkhamron P, Sudasna J.
Thyroid functions in children with Down's syndrome.
J Med Assoc Thai. 2008;91(1):56-61. PubMed abstract

Viegelmann G, Low Y, Sriram B, Chu HP.
Achalasia and Down syndrome: a unique association not to be missed.
Singapore Med J. 2014;55(7):e107-8. PubMed abstract / Full Text

Walker JC, Dosen A, Buitelaar JK, Janzing JG.
Depression in Down syndrome: a review of the literature.
Res Dev Disabil. 2011;32(5):1432-40. PubMed abstract

Watts R, Vyas H.
An overview of respiratory problems in children with Down's syndrome.
Arch Dis Child. 2013;98(10):812-7. PubMed abstract

Worley G, Crissman BG, Cadogan E, Milleson C, Adkins DW, Kishnani PS.
Down Syndrome Disintegrative Disorder: New-Onset Autistic Regression, Dementia, and Insomnia in Older Children and Adolescents With Down Syndrome.
J Child Neurol. 2015;30(9):1147-52. PubMed abstract

Worley G, Shbarou R, Heffner AN, Belsito KM, Capone GT, Kishnani PS.
New onset focal weakness in children with Down syndrome.
Am J Med Genet A. 2004;128A(1):15-8. PubMed abstract / Full Text

Zemel BS, Pipan M, Stallings VA, Hall W, Schadt K, Freedman DS, Thorpe P.
Growth Charts for Children With Down Syndrome in the United States.
Pediatrics. 2015;136(5):e1204-11. PubMed abstract / Full Text

de Graaf G, Buckley F, Skotko BG.
Estimation of the number of people with Down syndrome in the United States.
Genet Med. 2017;19(4):439-447. PubMed abstract