Background
Epidemiology
- Most common chromosomal disorder, occurring in 1:800 live births
- Most common genetic cause of mental impairment
Pathophysiology
- Trisomy 21, most commonly caused by meiotic non-disjunction
Clinical Manifestations
- Presents at birth with hypotonia, short neck, single palmar crease and characteristic facial features, which include flat facial profile, oblique palpebral fissures, and epicanthic folds
- Mental impairment
- Half will have congenital heart disease
- Increased risk of leukemia, including acute lymphoblastic leukemia and acute myeloid leukemia
- Increased risk of pneumonia
- Early Alzheimer disease starting around age 40 years
- Median age of death is 47 years
