Prenatal diagnosis of congenital adrenal hyperplasia due to 21-hydroxylase deficiency with DNA analysis.

Six families at risk of having a child with 21-hydroxylase deficiency (21-OHD) requested prenatal diagnosis by DNA analysis. This was performed by Southern hybridization mainly using the endonuclease-probe combination of TaqI-21-hydroxylase (21-OHase) complementary DNA (cDNA). In three families, the probands were found to have deletion of a 3.7 kb fragment corresponding to the functional 21-OHase gene (21-OHase B gene). In the three fetuses tested, genomic DNA extracted from the chorionic villi had the 3.7 kb fragment and all were judged to be unaffected. In the other three families, DNA analysis was uninformative in the detection of 21-OHD and was also unable to determine carrier status with 21-OHase cDNA. In one of these three families, however, linkage analysis detected restriction fragment length polymorphism (RFLP) with cDNA for the fourth component of the complement (C4).