SALT-WASTING CONGENITAL ADRENAL-HYPERPLASIA - DETECTION OF MUTATIONS IN CYP21B GENE IN A CHILEAN POPULATION

The steroid 21-hydroxylase deficiency (21OHD) is the most frequent cau se of congenital adrenal hyperplasia. We have characterized the diseas e-causing mutations in the 21-hydroxylase genes of 63 patients with sa lt-wasting congenital adrenal hyperplasia from a Chilean population of Hispanic origin, a group that has been scarcely evaluated. Using alle le-specific PCR, lesions were identified in 97 chromosomes out of 126 tested (77%). The most frequent findings were the gene deletion or lar ge gene conversion (LGC) = 22.9%, I2 splice = 19%, R357W = 12.7%, and Q319X = 10.5%. We did not find alleles with the mutation F308insT and we found three alleles with the cluster E6. The frequency of the point mutation R357W was at least two times more frequent than the one foun d in Caucasians populations, but similar to that communicated in Asian populations; this finding may be explained by the Asian ancestry of o ur South-Amerindian population. The frequency of Q319X was also high, similar only to those patients studied in Italy and in a neighboring A rgentinian population. In summary, this is a genetic characterization of 21OHD made in an almost pure Hispanic population in Latin America. The high frequency of deletion of CYP21B gene, I2 splice, R357W, and Q 319X mutations probably reflects the European-Caucasian-Spanish influe nce of the conquerors, mixed with Amerindians of Asian ancestry and mo dulated by other European immigrations.