Objective: To identify pathogenic mutations in 25 Chinese pedigrees affected with congenital adrenal hyperplasia (CAH).
Methods: 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.
Results: 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.
Conclusion: The detection of CYP21A2 gene mutations can facilitate appropriate genetic counseling and prenatal diagnosis for the affected pedigrees.