Down syndrome is the most common genetic cause of cognitive or intellectual disability, with a prevalence of 1 in 691 births.
Characteristic physical features include brachycephaly with a flat occiput; epicanthal folds and upslanting palpebral fissures; Brushfield spots in the iris; low nasal bridge; low-set ears; broad neck; and small hands with transverse crease.
Individuals with Down syndrome have a higher frequency of congenital and acquired medical conditions, including congenital heart defects and audiologic, vision, gastrointestinal, hematologic, and thyroid issues.
Global developmental delay is common; however, cognitive abilities vary greatly, with IQ ranging from mild to moderate intellectual disability. Behavioral difficulties, if present, tend to be age-related (e.g., hyperactivity and impulsiveness in younger children; withdrawal and anxiety in older adolescents). Screening and clinical observation of symptoms suggestive of autism spectrum disorder is recommended.
Early interventional therapies (e.g., speech therapy, physical therapy, occupational therapy) and individualized educational programs/resources are essential to maximize the potential of a person with Down syndrome.
Down syndrome (DS), or trisomy 21, is the most common genetic form of intellectual disability, occurring in 1 in 691 births. In addition to having characteristic physical features, short stature, and hypotonia, individuals with DS have a distinctive cognitive and behavioral profile. They also have a higher frequency of associated medical conditions, including congenital heart defects, and gastrointestinal, thyroid, hematologic, audiologic, and visual abnormalities.
History and exam
Key diagnostic factors
- common physical exam features
- congenital heart disease
- gross motor delay
- language delay
- cognitive disability
- hearing loss
- autism spectrum disorder
Other diagnostic factors
- congenital gastrointestinal disorder
- feeding difficulty
- behavioral difficulties
- advanced maternal age
- previous child with Down syndrome
- parental karyotype with a translocation
1st investigations to order
- chromosomal karyotype
Investigations to consider
- abdominal x-ray
- hearing test
- thyroid function tests
- vision exam
- dental exam
- developmental evaluation
- psychoeducational evaluation
- total IgA and antitissue transglutaminase antibodies
- cervical spine x-rays
Kishore Vellody, MD
Associate Professor of Pediatrics
Down Syndrome Center of Western Pennsylvania
Children’s Hospital of Pittsburgh
KV declares that he has no competing interests.
Dr Kishore Vellody would like to gratefully acknowledge Dr Jeannie Visootsak, the previous contributor to this topic.
JV declared that she had no competing interests.
Nirupama S. Madduri, MD
Vanderbilt University School of Medicine
W. Carl Cooley, MD
Crotched Mountain Foundation
Center for Medical Home Improvement
Adjunct Professor of Pediatrics
Dartmouth Medical School
WCC declares that he has no competing interests.
- Isolated hypotonia
- Zellweger syndrome
- Congenital hypothyroidism
- Medical care of adults with Down syndrome: a clinical guideline
- Guidelines on thyroid disorder in children and young people with Down syndrome: surveillance and when to initiate treatment
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