High-resolution melting curve (HRM) analysis to establish CYP21A2 mutations converted from the CYP21A1P in congenital adrenal hyperplasia.

BACKGROUND

Congenital adrenal hyperplasia (CAH) is an autosomal recessive disease of an inborn error of steroid metabolism in humans. More than 90% of CAH cases are caused by mutations of the steroid 21-hydroxylase (CYP21A2) gene, and approximately 75% of the defective CYP21A2 genes are generated through an intergenic recombination with the neighboring CYP21A1P pseudogene.

METHODS

A high-resolution melting (HRM) curve analysis was designed to characterize 11 mutation sites of the CYP21A2 gene that commonly appeared in 21-hydroxylase deficiency. Among these 11 mutations, 9 were found in CAH patients, and 2 were mutations created from normal individuals.

RESULTS

From the HRM analysis using 6 fragments of amplicons, we have successfully identified these 11 common disease-causing mutations of the CYP21A2 gene, among which 3 showed 3 distinguishable melting plots; the heteroduplexes showed an upcurved plot, a horizontal plot of homoduplexes of wild-type (WT), and a downcurved plot of homoduplexes of compound mutations.

CONCLUSIONS

The HRM analysis is a 1-step of non-gel resolution technique which saves time and is a low-cost method to undertake such a program for screening CAH patients with the 21-hydroxylase deficiency caused by intergenic conversions from the neighboring CYP21A1P pseudogene.