A 6-month-old infant presents with progressive neurological dysfunction, cholestasis, bilateral cataracts, and chronic diarrhea. A diagnosis is made of a bile acid metabolism defect due to deficiency in the sterol 27-hydroxylase gene. Which of the following would be expected to be an additional finding in this infant?

Question

Quizplus · Accepted Answer

The alternative bile acid synthesis pathway involves hydroxylation of cholesterol at the 27 position by the mitochondrial enzyme sterol 27-hydroxylase (CYP27A1). This alternative pathway is referred to as the "acidic" pathway of bile acid synthesis. The product of this pathway is chenodeoxycholic acid, the same as for the classic pathway initiated by CYP7A1. However, the acidic pathway does not lead to the synthesis of cholic acid; so this bile acid and its metabolites would be reduced in individuals with a deficiency in CYP27A1. Although the acidic pathway accounts for no more than 6% of total bile acid production, it is an important as evidenced by the symptoms seen in infants harboring the defective gene.

A 6-Month-Old Infant Presents with Progressive Neurological Dysfunction, Cholestasis, Bilateral