Abstract
Congenital adrenal hyperplasia (CAH) comprises a group of autosomal recessive disorders caused by an enzymatic deficiency which impairs the biosynthesis of cortisol and, in the majority of severe cases, also the biosynthesis of aldosterone. Approximately 95% of all CAH cases are caused by mutations in the steroid 21-hydroxylase gene (CYP21A2).
The CYP21A2 gene and its inactive pseudogene (CYP21A1P) are located within the HLA class III region of the major histocompatibility complex (MHC) locus on chromosome 6p21.3. In this study, we describe chimeric CYP21A1P/.
CYP21A2 genes detected in our patients with 21-hydroxylase deficiency (21OHD). Chimeric CYP21A1P/.
CYP21A2 genes were present in 171 out of 508 mutated CYP21A2 alleles (33.8%). We detected four types of chimeric CYP21A1P/.
CYP21A2 genes: three of them have been described previously as CH-1, CH-3, CH-4, and one type is novel. The novel chimeric gene, termed CH-7, was detected in 21.4% of the mutant alleles.