Prenatal Diagnosis of Steroid 21-Hydroxylase Deficiency by Allele-Specific Amplification

Objective: Congenital adrenal hyperplasia due to steroid 21-hydroxylase deficiency (21-OHD) is the most common cause of ambiguous genitalia in females at birth. Here, we report the first prenatal diagnosis of 21-OHD by DNA analysis in Hungary. Methods: Allele-specific amplification (ASA) of the DNA obtained by chorionic villus sampling was performed. Results: The fetus had a homozygous nonsense mutation (Gln318Stop), suggesting a salt-wasting phenotype. Dexamethasone treatment of the mother was started on the 8th gestational week and, as the fetus was an affected female, it was continued until term. The newborn had normal external genitalia at birth, and severe salt-wasting crisis and postnatal virilization was prevented by mineralo- and glucocorticoid replacement therapy. Conclusion: 21-OHD was genotyped by ASA, and virilization of the fetus was prevented by antenatal dexamethasone therapy.