[Detection of steroid 21-hydroxylase gene variation among normal Chinese and patients with congenital adrenal hyperplasia].

Genomic DNA from 40 unrelated healthy individuals and 16 families affected with 21-hydroxylase deficiency were digested with restriction enzyme Taq I followed by Southern blot and hybridization using a 21-hydroxylase (21-OH) gene cDNA probe. In healthy individuals the number of copies of 21-OHB gene was constant while that of 21-OHA gene was variable including deletion and duplication. In addition, we found an extra 5.6 kb band in one normal person and in one CAH family. Among the 16 affected families, 19% of 21-OHB gene were deleted. No homologous deletion was found. The frequency of deletion is lower than that reported in the literature. There was variation in the copy-number of 21-OHA gene among patients with CAH, yet no difference was found between the patients and normal persons. The information on prenatal diagnosis of CAH is briefly discussed.