Down's Syndrome (Trisomy 21)

• Most common single cause of mental retardation: 1.2/1000
• Only a small fragment of chromosome 21, 21QQ22.1-21QQ22.2 fragment needed in triplicate to produce Down's.
• Incidence increases with advanced maternal age
• 44% of patients live to age 60
• Diagnosis is by karyotyping
• Antenatal diagnosis offered to all pregnant women over the age of 35

Clinical Features

• Bradycephaly
• Microcephaly
• Epicanthic Folds (a vertical fold of skin on either side of the nose)
• Brushfield spots
• Small low-set ears
• Hearing Loss
• Fissured Tongue
• Simian creases
  
• Clindactyly (permanent deviation or turning aside of finger)
• Hypotonia (delayed movements) very prominent
• Heart Disease, Hypothyroidism and leukemia are common
• Older patients develop Alzheimer/amyloid changes