Question

An infant born to a 36-year-old Caucasian female demonstrates some dysmorphic facial features and a dysmorphic murmur at the left stall border. Karyotype analysis is consistent with trisomy 21. Which of the following additional findings would be most expected in this infant?

A. Cleft palate
B. Polydactyly
C. Single palmar crease
D. Rocker-bottom feet
E. Macrocephaly
F. Macroorchidism

Answer 1

The most expected finding in an infant diagnosed with trisomy 21, or Down syndrome, is a single palmar crease. This is a distinctive physical characteristic frequently observed in individuals with Down syndrome.

Step-by-step explanation:

An infant with a karyotype analysis consistent with trisomy 21, also known as Down syndrome, may have various specific physical characteristics. Among the options listed, the most expected finding in an infant with Down syndrome would be a single palmar crease. This is a distinctive feature where the usual two creases found on the palm of the hand merge into one. Down syndrome is associated with certain dysmorphic features, including a flat facial profile, slanted eyes, and a protruding tongue. While other options such as cleft palate or polydactyly are possible anomalies, they are not as characteristically associated with Down syndrome as the single palmar crease.