Congenital abnormalities

Question 1

What are the chromosomal abnormalities in:

1. Down’s syndrome?
2. Edwards syndrome?
3. Patau’s syndrome?
4. Klinefelter’s syndrome?
5. Turners syndrome?

How do they present?

Answer 1

1. Downs = trisomy 21
2. Edwards = trisomy 18 - major structutal abnormalities, fetus die in utero or shortly after birth
3. Patau’s = trisomy 13 - major structutal abnormalities, fetus die in utero or shortly after birth
4. Klinefelter’s = 47 XXY - male, normal intellect, small testes, infertile
5. Turners = X0 - female, infertile, norma intellect

Question 2

What are characteristics of Downs syndrome?

Answer 2

• Mental retardation
• Decreased or poor muscle tone
• Short neck, with excess skin at the back of the neck
• Flattened facial profile and nose
• Small head, ears, and mouth
• Upward slanting eyes, often with a skin fold that comes out from the upper eyelid and covers the inner corner of the eye
• White spots on the colored part of the eye (called Brushfield spots)
• Wide, short hands with short fingers
• A single, deep, crease across the palm of the hand
• A deep groove between the first and second toes

Question 3

Risk factors for Downs syndrome?

Answer 3

• High materal age
• Previous affected baby (1% risk)
• Balanced parental translocation (rare)

Question 4

What sugguest a high chance of Downs during pregnancy?

Answer 4

Dating scan: (11-13+6 weeks)

• Thickened stuctural abnormalities
• Absent or shortened nasal bone
• Triscuspid regurgitation

Blood tests:

• Low PAPP-A (1st trimester)
• High B-hCG (1st/2nd trimester)
• Low AFP (1st/2nd trimester)
• Low oestriol (2nd trimester)
• High inhibin (2nd trimester)

Question 5

What is the triple test?

When is it offered?

Answer 5

Blood test at 16 weeks

AFP, hCG + oestradiol

Reserved for when screening done >14 weeks as translucency scan not available

Question 6

How is Downs then diagnosed?

Answer 6

Amniocentesis (15 weeks) & CVS (11 weeks) = diagnostic test