Rapid identification of deoxyribonucleic acid sequence differences in cytochrome P-450 21-hydroxylase (CYP21) genes with denaturing gradient gel blots.

Denaturing gradient gel electrophoresis was used to identify single-base differences in the cytochrome P-450 21-hydroxylase (CYP21) genes of 132 unrelated control individuals and family members of three unrelated patients with 21-hydroxylase deficiency. The salt-wasting variety was caused by gene deletion and gene conversion/deletion mutations in affected members of two families studied. The simple virilizing form, present in the third family, was caused by an apparent point mutation not detectable by routine Southern blots. We have detected many restriction fragment melting polymorphisms in the CYP21 genes of the members of both salt-wasting families and normal individuals with denaturing gradient gel electrophoresis. We also identified a restriction fragment melting polymorphism specific for the simple virilizing patient in the third family. The data demonstrate that the CYP21 genes are highly polymorphic and that denaturing gradient gel electrophoresis is useful for genomic deoxyribonucleic acid analysis of patients with 21-hydroxylase deficiency.