Linkage between I172N mutation, a marker of 21-hydroxylase deficiency, and a single nucleotide polymorphism in Int6 of CYP21B gene: a genetic study of Sardinian family.

Congenital adrenal hyperplasia (CAH) is a genetic disorder due to 21-hydroxylase deficiency. More than 90% of CAH cases are caused by mutations of CYP21B gene, most of which are the result of microconversion events between the functional gene and its pseudogene. Using a combination of RFLP and direct sequencing analysis, in this paper we describe the genetic study of a Sardinian family carrying I172N mutation in linkage with a SNP namely 1636 Int6. The characterization of new polymorphisms in CYP21B can improve the analysis of segregation of CYP21B mutated alleles especially in genetic familial studies. The analysis of linkage between specific mutations and this SNPs, especially if focused on genetic familial studies, may improve the quality of genetic analysis of 21-hydroxylase deficiency.