CONGENITAL ADRENAL-HYPERPLASIA - MOLECULAR CHARACTERIZATION

OBJECTIVE: To study the molecular defects of congenital adrenal hyperp lasia (CAH). STUDY DESIGN: Twenty Chinese patients, including 8 with s alt-wasting (SW) type CAH, II with simple virilizing (SV) type CAH and 1 with nonclassical (NC) type CAH, were recruited. Two rounds of the polymerase chain reaction (PCR) were used to study the 21-hydroxylase gene (CYP21). The primary PCR amplified CYP21-specific DNA fragments, and the secondary PCR used products from the primary PCR for analysis of amplification-created restriction sites (ACRS) and direct DNA seque ncing. In all patients, ACRS analysis was done at 12 possible mutation sites, and then direct DNA sequencing was performed to confirm or def ine the molecular defects. RESULTS: Tell different mutations, includin g nine point mutations and gross gene deletion or conversion, were fou nd in this study. Of the nine point mutations, eight could be easily d etected by ACRS analysis. The three most common mutations were codon ( CD)172 t-->a (I172N), IVS-II 656 c/a-->g, and gross gene deletion or c onversion, accounting for 27.5% (11/40 alleles), 25% (10/40) and 20% ( 8/40) of all identified mutations, respectively. All SW patients were compound heterozygotes of IVS-II 656, gross gene deletion or conversio n, or other severe defects, including CDs236 (t-->a) (I236N)+ 237 (t-- >a) (V237E)+239 (t-->a) (M239K), CD306 (+ t), CD318 (c-->t) (Q318X) an d CD356 (c-->t) (R356W) mutations. All SV patients had one allele with a CD172 (I172N) mutation. One allele of an NC patient had a CD183 (c- ->g) (D183E) mutation, and the other allele was not defined. In the wh ole series,four alleles (10%) had more than one mutation. CONCLUSION: We found 10 different mutations in this study. The correlation between genotypes and phenotypes was compatible with the reported data. Two r ounds of PCR and ACRS analysis may provide important information for g enetic counseling, prenatal diagnosis and management of families at ri sk for CAH.