Question 152

Question:

A neonate is born with low-set ears, rocker-bottom feet, micrognathia, clenched hands and a prominent occiput. Cytogenetic studies would most likely reveal which of the following?

Correct Answer: D.  Trisomy 18

This is Edwards syndrome, or trisomy 18. The clenched hands, rocker-bottom feet, and micrognathia are a characteristic feature.
Trisomy 13 is Patau syndrome which is usually characterized by midline defects such as cleft lip/cleft palate and holoprosencephaly. Polydactyly and micropthalmia are characteristic features.
Trisomy 16 is the most common chromosomal cause of spontaneous abortion in utero.
Trisomy 21 is Down syndrome, which is characterized by flat facial profile, prominent epicanthal folds, single palmar crease, duodenal atresia and congenital heart disease.
Trisomy 8 frequently results in miscarriage and those that survive to term usually exhibit trisomy 8 mosaicism. This syndrome results in mental retardation, relatively specific facies, absent or dysplastic patellas, joint contractures and other anomalies.