A case of 3β-hydroxysteroid dehydrogenase type II (HSD3B2) deficiency picked up by neonatal screening for 21-hydroxylase deficiency:: Difficulties and delay in etiologic diagnosis

Background: 3 beta - Hydroxysteroid dehydrogenase type II deficiency, a rare form of congenital adrenal hyperplasia, is characterized by varying degrees of salt loss and incomplete masculinization in males and mild virilization or normal external genitalia in females. The clinical signs may be difficult to recognize, increasing the risk of a neonatal adrenal crisis. In addition, elevated 17 alpha - hydroxyprogesterone and androstenedione levels due to peripheral HSD3B1 activity may lead to a delay of the correct diagnosis and even to misdiagnosis as CYP21 deficiency. Method: We report a patient who was detected on neonatal screening for 21- hydroxylase deficiency, in part because of cross- reactivity in the commonly used assay. Results: The diagnostic difficulties in this case were overcome by the use of more specific antibodies. Conclusion: This case emphasizes the importance of confirming the etiological diagnosis with molecular genetic analyses.