Down's syndrome is the most common genetic cause of cognitive or intellectual disability, with a prevalence of 1 in 800 births worldwide.
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's syndrome have a higher frequency of congenital and acquired medical conditions, including congenital heart defects and audiological, vision, gastrointestinal, haematological, and thyroid issues.
Global developmental delay is common; however, cognitive abilities vary greatly, with IQ ranging from mild to moderate intellectual disability. Behavioural difficulties, if present, tend to be age-related (e.g., hyperactivity and impulsiveness in younger children; withdrawal and anxiety in older adolescents).
Early interventional therapies (e.g., speech therapy, physiotherapy, occupational therapy) and individualised educational programmes/resources are essential to maximise the potential of a person with Down's syndrome.
Down's syndrome (DS), or trisomy 21, is the most common genetic form of intellectual disability, occurring in 1 in 800 births worldwide. In addition to having characteristic physical features, short stature, and hypotonia, individuals with DS have a distinctive cognitive and behavioural profile. They also have a higher frequency of associated medical conditions, including congenital heart defects, and gastrointestinal, thyroid, haematological, audiological, and visual abnormalities.
History and exam
Key diagnostic factors
- presence of risk factors
- common physical examination features
- congenital heart disease
- gross motor delay
- language delay
- cognitive disability
- hearing loss
- autism spectrum disorder
Other diagnostic factors
- congenital gastrointestinal disorder
- feeding difficulty
- behavioural difficulties
- advanced maternal age
- previous child with Down's syndrome
- parental karyotype with a translocation
1st investigations to order
- chromosomal karyotype
- FBC with differential
- hearing test
- thyroid function tests
- vision examination
Investigations to consider
- abdominal x-ray
- Isolated hypotonia
- Zellweger's syndrome
- Congenital hypothyroidism
- Health supervision for children and adolescents with Down syndrome
- Medical care of adults with Down syndrome: a clinical guideline
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