Molecular characterization of 21-hydroxylase deficiency in 70 Italian families.

Seventy Italian families affected by 21-hydroxylase deficiency were studied in order to evaluate the distribution of mutations. The coding P450c21B gene, the highly homologous P450c21A pseudogene and the linked C4A, C4B and DRB genes, mapping within the major histocompatibility complex region, were studied by multiple restriction analysis and in vitro amplification. In the affected individuals, 21.4% of the chromosomes were found to carry either gene deletions or large and small gene conversions. Our findings, consistent with previous reports in other ethnic groups, provide further evidence for the genetic heterogeneity of the disease.