Research in Medicine

Background: Congenital Adrenal Hyperplasia (CAH) is an inherited hereditary autosomal recessive heredity, which is often induced by mutation in the CYP21A2 gene. The aim of this study was to determine the prevalence of cluster exon 6 mutation among patients with CAH deficient in 21-OHD enzyme in Iranian population.

Materials and Methods: This is a descriptive study and Blood samples were collected from 25 patients with CAH who referred to Ali Asghar Hospital in Tehran. After extraction of genomic DNA, the region containing the cluster gene exon 6 gene was amplified by PCR and then sequenced. Finally, by analyzing sequences, the frequency of cluster mutation exon 6 was determined in the population studied.

Results: 15 patients (60%) had an cluster mutation of exon 6, so that in all of them, three mutations V236E, I236N and M238K were observed as heterozygote. This mutation in the healthy parents of these patients were also identified as heterozygote.

Conclusion: it seems that cluster E6 mutation in the heterozygote form alone does not lead to disease, and it is necessary to examine the presence of other mutations in the gene. While this mutation may be present as compound heterozygote along with other mutations in the rest of the exons in patients.