Mutations in the CYP21B gene in a Chilean population with simple virilizing congenital adrenal hyperplasia

Steroid 21-hydroxylase deficiency (21OHD) compromises about 95% of all case s of congenital adrenal hyperplasia. We have characterized the disease-caus ing mutations in the steroid 21-hydroxylase genes of 19 Chilean patients (1 2 females and 7 males) with the simple virilizing (SV) form of 21OHD and co mpared them with other SV-populations. Using allele-specific polymerase cha in reaction, we identified lesions in 28 chromosomes out of 38 tested (73.7 %). The most frequent finding was the mutation I173N= 12/38 (31.6%) similar as described in Caucasian, Asian and other Hispanic populations, where thi s mutation represents around 20-40% of the genetic defects in the CYP21B ge ne. The mutation V282L=4/38 (10.5%) and deletion (Del) or large gene conver sion (LGC)=3/38 (7.9%) were also frequently detected. Only 2 alleles carrie d the mutation 12 splice (5.3%), this frequency is lower than that reported in Caucasian or in Mexican populations. We did not find alleles with the m utations R357W, Cluster E6, P31L and P454S in these patients. The complete genotype was determined in 11/19 patients (58%) and one allele in 6/19 pati ents (31.6%). In summary, about 30% of the Chilean population with SV 21OHD presented the missense mutation I173N as described in other populations. T he frequency of the other lesions showed differences even between populatio ns with similar genetic background. (C)2000, Editrice Kurtis.