Down Syndrome

Question 1

What kind of screening is in place to pick up down syndrome during pregnancy?

Answer 1

First trimester screening (risk of DS only)
- Non-fasting blood test at 10 weeks
○ Down syndrome markers: PAPP-A tends to be low andβ-hCG high in Down’s syndrome
- US at 12 weeks (range 11 weeks and 1 day to 13 weeks and 6 days)
○ Nuchal translucency (>2.5mm suggestive of chromosomal abnormalities)
○ Nasal bone: ossified nasal bone indicates lower risk of DS

• Alternative is cell-free DNA screening(NIPT)

Second trimester screening
- For risk assessment of:
○ DS, Edward syndrome, open neural tube defects
- ‘Quadruple’ blood test: ○ alpha-feto protein (low), human chorionic gonadotrophin (high), unconjugated estriol (low) and inhibin A

Question 2

Neonatal clinical features of down syndrome

Answer 2

Face

• Flat nasal bridge
• Ears poorly formed and small, and low set

Eyes

• Upslanting papebral fissures (top of eye)
• Medial epicanthic fold (upper eyelid fold covering inner corner)
• Brushfield spots in iris

Mouth

• Downturned mouth
• Macroglossia
• Glossoptosis
• Dental problems

Peripheries
• Hands broad, short fingers
• Clinodactyly of the fifth fingers (short middle phalanges lead to incurving)
• single palmar creases- simian crease
• Gap between first and second toes (Sandal deformity)
• Hypotonia

Other
• Excessive nuchal folds
• Brachycephaly

Question 3

Associated malformations with down syndrome

Answer 3

• Congenital heart disease in 40-50%
	○ Esp. ASVD
	○ Tetralogy of fallot
• Gastrointestinal
	○ Duodenal atresia
	○ Imperforate anus/anal atresia
	○ Hirschsprung disease
• Eyes
	○ Strabismus
	○ Congenital optic lens
• Sleep disorders e.g. OSA
• Hypothyroidism
• Feeding difficulties
• Intellectual disability of varying degree
• All have neuropathological changes of Alzheimer disease by 35-40 years with clinical onset in the early 50s

Question 4

What is the GS diagnosis?

Answer 4

Genetic confirmation with banded karyotype (10-14 days to get results), FISH if urgent

Question 5

What must be done when a dx is suggested prenatally, and at birth?

Answer 5

Early family discussion

• genetic counselling regarding prenatal dx
• Educate
• Plan for delivery

At birth

• echo for cardiac defects
• TFTs exclude congenital hypothyroidism
• Newborn hearing screen
• Evaluate swallowing

Question 6

What must be done for management of down syndrome post-diagnosis?

Answer 6

Support

• Early follow up with paediatrician and GP
• Constant counselling
• Support: DS association of Victoria, support groups
• Respite if needed
• Access to financial support and benefits
• Early intervention and educational plan

General

• Growth
• DS growth charts
• Initial feeding difficulties common
• Avoid obesity

Monitoring other diseases

• Thyroid
  
  • Yearly TFTs due to increased risk of hypothyroidism
• Coeliac disease screening at 3-4 years, or testing if symptomatic
• Leukaemia - no routine screening, but at increased risk
• Hearing - initial screen and repeat as indicated
• Sleep - risk of OSA
• Vision - cataracts, refractive errors, strabismus
• Development
  
  • Specific therapy
  • Behavioural adjustment