Downs Syndrome

Question 1

Describe the risk of Down’s Syndrome in relation to maternal age

Answer 1

20y 1 in 1,500
30y 1 in 800
35y 1 in 270
40y 1 in 100
45y 1 in 50 or greater

Question 2

Describe the 3 mechanisms by which Down’s syndrome can arise

Answer 2

1. Nondisjunction (94%)
2. Robertsonian translocation (onto chromosome 14) [5% or higher if parent carries translocation themselves]
3. Mosaicism (1%)

Question 3

Physical features of Down’s Syndrome

Answer 3

face:
- upslanting palpebral fissures
- epicanthic folds
- Brushfield spots in iris
- protruding tongue
- small low-set ears, round/flat face
- flat occiput

Other:
- single palmar crease
- pronounced gap between big and first toe
- hypotonia
- congenital heart defects
- duodenal atresia
- Hirschsprung’s disease

Question 4

Cardiac associations with Down’s Syndrome

Answer 4

• endocardial cushion defect (AKA atrioventricular septal canal defects)
• ventricular septal defect
• secundum atrial septal defect
• tetralogy of Fallot
• isolated patent ductus arteriosus

Question 5

Complications of Down’s Syndrome later in life

Answer 5

• Subfertility: males = always due to impaired spermatogenesis. Females = subfertile. + increased incidence of problems with pregnancy and labour
• learning difficulties
• short stature
• repeated respiratory infections
• hearing impairment from glue ear
• ALL
• hypothyroidism
• Alzheimer’s disease
• atlantoaxial instability