Diagnosis of the first Japanese patient with 3-oxo-delta4-steroid 5beta-reductase deficiency by use of immunoblot analysis.

UNLABELLED: A 3-oxo-delta4-steroid 5beta-reductase (5beta-reductase) deficiency is difficult to diagnose because severe liver damage can result in a similar pattern of metabolite excretion. We investigated the usefulness of immunoblot analysis for diagnosis of 5beta-reductase deficiency and quantitatively analysed urinary bile acids by gas chromatography-mass spectrometry in a 5-month-old Japanese boy with severe neonatal cholestasis associated with hypertyrosinaemia. A liver sample was examined by immunoblot analysis using monoclonal antibodies against 5beta-reductase. Urinary 3-oxo-delta4 bile acids accounted for 88.3% of total bile acids, 5alpha-bile acids for 0.9%, and primary bile acids for 9.1%. Immunoblot analysis of the liver tissue showed an indistinct band of 5beta-reductase.
CONCLUSIONS: These findings suggest that this patient had a secondary 5beta-reductase deficiency due to severe liver damage, even though 3-oxo-delta4 bile acids constituted more than 70% of total urinary bile acids. However, the patient may possibly have had an inherited 5beta-reductase deficiency.