Distribution of the V281L mutation of the CYP21 gene in Israeli congenital adrenal hyperplasia patients and its association with HLA- B14.

The V281L mutation in the CYP21 gene, responsible for non classical CAH, was studied in patients of different Israeli ethnic groups and compared to the data on healthy population. The Israeli population consists of many ethnic groups which can be divided into three main entities: Ashkenazi, Non Ashkenazi and Israeli Arabs. The frequency of V281L mutation in the patients of the different ethnic groups varied and was a reflection of the frequency found in the healthy population namely: very high in the Ashkenazi (74%) , lower in the non Ashkenazi (39%) and very low in the Israeli Arabs (2.9%) . The phenomenon of strong association between the HLA B14 allele and the V281L mutation found in our population study, as well as in other studies, confirmed by linkage found in patient families, can be used to distinguish between homozygote and hemizygote carrying the V281L mutation, when no family study is available. The relevance of this finding is especially important in cases of genetic counseling when a carrier of a severe mutation is involved.