Genetic analysis and prenatal diagnosis for 25 Chinese pedigrees affected with congenital adrenal hyperplasia due to 21-hydroxylase deficiency

Abstract

To identify pathogenic mutations in 25 Chinese pedigrees affected with congenital adrenal hyperplasia (CAH). Mutations of the CYP21A2 gene were detected with locus-specific PCR/restriction endonuclease analysis, multiplex ligation-dependent probe amplification assay, and direct sequencing of the entire CYP21A2 gene. Prenatal diagnosis was offered to fetuses at risk for CAH. All 50 alleles of the CYP21A2 gene carried by the 25 pedigrees were successfully delineated. Large deletions and conversions have accounted for 16 (32%) of the alleles, which included 9 entire CYP21A2 gene deletions, 6 chimeric CYP21A1P/CYP21A2 genes, and 1 partial conversion of the CYP21A2 gene. For the remaining 34 alleles, there were 9 micro-conversions and 4 de novo mutations [including a previously unreported c.62G>A (p.Trp21X) mutation]. Prenatal diagnosis was provided for 28 fetuses with a high risk for CAH, among whom 8 were found to be affected. The detection of CYP21A2 gene mutations can facilitate appropriate genetic counseling and prenatal diagnosis for the affected pedigrees.