defect in oxysterol 7α-hydroxylase

A defect in the conversion of 27-hydroxy-cholesterol to 7α,27-dihydroxy-cholesterol due to a deficiency in oxysterol 7α-hydroxylase (CYP7B1), an enzyme specifically involved in the acidic pathway, causes severe neonatal liver disease.

This is probably due in part to the accumulation of monohydroxyl bile acid species, with marked cholestatic and hepatotoxic capabilities.

This defect, resulting from a mutation in the gene, reveals the importance in humans of this alternative pathway in early life.