defect in 3β-hydroxy-C27-steroid dehydrogenase/isomerase

This enzyme catalyzes the oxido-reduction of the 3β-hydroxyl group of 7α-hydroxycholesterol. Its deficiency is the most common defect in bile acid synthesis.

Individuals with autosomal recessive mutations in the encoding gene, HSD3B7, fail to synthesize bile acids normally and develop a form of progressive liver disease characterized by cholestatic jaundice and malabsorption of lipids and lipid-soluble vitamins.