Analysis of common genetic mutations in a cohort of children with salt wasting form of Congenital Adrenal Hyperplasia

Steroid hydroxylase deficiency due to CYP21A2 gene mutation is the most common cause of Congenital Adrenal Hyperplasia (CAH). Mutation spectrum in Sri Lankan CAH patients has not been investigated adequately. This study attempted to study the spectrum of mutations in CYP21A2 gene in 30 patients with salt wasting form of CAH in Sri Lanka. Allele specific polymerase chain reaction was carried out using mutation site specific primers for eight mutations (P30L, I2G, 8bp deletion, I172N, E6 cluster, V281L, Q318X and R356W) reported as frequently occurring in other populations. Fourteen patients had homozygous mutations; six patients were compound heterozygotes as determined by investigating parents of the patients, one patient had a large gene deletion which was previously reported and the remaining patients had at least one heterozygous mutation. The following allele frequencies were observed for each mutation P30L-10%, I2G- 40%, 8bp-18.33%, I172N-3.33%, E6 cluster- 5%, Q318X-40% and R356W-3.33%. V281L mutation was not observed in the study cohort. DNA sequencing revealed a novel mutation G292S in one patient. This is the first report describing a broad spectrum of mutations in CYP21A2 gene in Sri Lankan patients with CAH. Mutation frequencies did not vary from other ethnic groups reported around the world.