Genetic analysis of the steroid 21-hydroxylase gene following in vitro amplification of genomic DNA.

The 5′ end of the steroid 21-hydroxylase B gene encompassing putative control regions and the first 3 exons, has been selectively amplified in vitro from a number of patients with congenital adrenal hyperplasia caused by a deficiency of this enzyme. Sequence analysis has revealed a number of isolated instances of gene conversion to the 21-hydroxylase A sequence. One mutation, a C to G transversion at the 3′ end of the second intron, thought to lead to incorrect splicing of the mRNA, was found in 11 subjects all with the classical form of the disease.