You are examining a 6-month-old infant who presents with a series of distinctive craniofacial and limb abnormalities. These abnormalities include microcephaly, micrognathia, ptosis, cleft palate, short thumbs, and syndactyly of the second and third toes. You suspect the infant is suffering from Smith-Lemli-Opitz syndrome and order a confirmatory test that includes analysis of the activity of which of the following enzymes?
A) ATP-citrate lyase
B) 7-dehydrocholesterol reductase
C) HMG-CoA reductase
D) mevalonate kinase
E) pyruvate carboxylase

Question

Quizplus · Accepted Answer

Smith-Lemli-Opitz syndrome is caused by a deficiency in the enzyme 7-dehydrocholesterol reductase, which is responsible for the final step in cholesterol biosynthesis.  Smith-Lemli-Opitz syndrome (SLOS) is caused by mutations in the gene encoding the terminal enzyme in cholesterol biosynthesis, that is, 7-dehydrocholesterol reductase.

You Are Examining a 6-Month-Old Infant Who Presents with a Series