AB167. Congenital adrenal hyperplasia (CAH) caused by mutations in the CYP21A2 and CYP11B1 gene of Vietnamese children patients

Abstract: 21-hydroxylase (CYP21A2) and 11β-hydroxylase (CYP11B1) are two important enzymes catalyzing conversion of adrenal and steroid hormone biosynthesis. While CYP11B1 only participates in cortisol synthesis pathway, CYP21A2 catalyzes conversion of both cortisol and aldosterone. Mutations in these two genes lead to congenital adrenal hyperplasia (CAH) which is a genetic disease resulting from autosomal recessive traits. The typical manifestations of this disease are virilization, salting loss, dehydration, hypertension and even gonad deformation in severe female inborn patients. Mutations in the CYP21A2 gene which occupy about 90% cases are the main cause contributing in CAH meanwhile CYP11B1 gene mutants accounting for just 5-8% cases are the second main cause of this disease. In our study, entire CYP21A2 and CYP11B1 gene were amplified by PCR and directly sequenced to detect mutations. In further research, the effect of mutations was predicted and evaluated by protein 3D modelling analysis and enzyme assay in COS-1 cell line. As the results, three novel mutations (IVS6+5G>T, R51K and Y395X) in the CYP11B1 gene were detected in Vietnamese children diagnosed suffering from CAH. In terms of CYP21A2 gene, three mutations including 30 kb deletion, I2 splicing and E246 frameshift were found and also described previously. In conclusion, the results of our study have considerable significance in early diagnosis through understanding the relationship between genotype and phenotype of patients. Furthermore, mutagenesis detection and analysis could assist doctors bring out genetic consultants for patients as well as their parents.

Keywords: Congenital adrenal hyperplasia (CAH); CYP11B1; CYP21A2; genetic disease; mutations