Trisomies

Question 1

Trisomy 21 (Down syndrome)

Answer 1

Can be due to

1. Translocation- NEED chromosomal studies of parents
   - If a parents is a carrier with a full translocation then 100% chance of Down syndrome recurring)-pretty rare
   - If a parent is a partial translocation, the risk if 15%
2. Nondisjunction
   - The risk for reoccurrence is the same for the gen popoulation (age 22 1/1500, age 40 1/90)

Question 2

What are the common abnormalities seen with Trisomy 21?

Answer 2

Hypotonia is the MOST common

W/o for Atlantoaxial instability

Dysplasia of the middle phalanx of the 5th finger
Ouch! Cardiac disease (AV canal, endocardial cushion defect)
Wide Gap betwen 1st and 2nd toe
Neck has excess skin in the back

Spots (Brushfields in eyes)
Y-picture protruding tongue
Nice transverse palmar (aka Simian crease)
Duodenal atresia (w/o for Hirschsprung too)
Really extensible joints
Oncology/leukemia risk
Moro reflex is incomplete
Ears are small and anomalous

Question 3

What are the common abnormalities seen with Trisomy 18?

Answer 3

• Rocker bottom feet
• Clenched fist
• Overlapping fingers (pathognomonic)
• Hypoplastic nails
• Seizures
• Prominent occiput, microcephaly, microophthalmia
• Low set malformed ears
• Horseshoe kidneys

Question 4

What are the common abnormalities seen with Trisomy 13?

Answer 4

• Punched out scalp lesions
• Cutis aplasia (pathognomonic)

Brain (holoprosencephaly, microcephaly)
Airs (low set ears)
Digits (extra digits)

Leukocytes (unique nuclear projections in neutrophils)
Uterus (bicornuate uterous and hypoplastic ovaries)
Cleft lip and palate (b/l)
Kidneys (cystic)