title: Gene conversion in steroid 21-hydroxylase genes.
abstract: The steroid 21-hydroxylase gene, CYP21B, encodes cytochrome P450c21, which mediates 21-hydroxylation. The gene is located about 30 kb downstream from pseudogene CYP21A. The CYP21A gene is homologous to the CYP21B gene but contains some mutations, including a C----T change which leads a termination codon, TAG, in the eighth exon. We found the same change in a mutant CYP21B gene isolated from a patient with 21-hydroxylase deficiency. Furthermore, a reciprocal change--i.e., a T----C change in the eighth exon of the CYP21A gene--was observed in the Japanese population and was associated with the two HLA haplotypes, HLA-B44-DRw13 and HLA-Bw46-DRw8. These changes may be considered the result of gene conversion-like events.
authors.affiliation: Department of Genetics, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Urabe
authors.forename: A
authors.initials: A
authors.lastname: Kimura
authors.forename: F
authors.initials: F
authors.lastname: Harada
authors.forename: T
authors.initials: T
authors.lastname: Iwanaga
authors.forename: T
authors.initials: T
authors.lastname: Sasazuki
mesh_terms: D000312:Adrenal Hyperplasia, Congenital; D001483:Base Sequence; D015139:Blotting, Southern; D002874:Chromosome Mapping; D005260:Female; D005785:Gene Conversion; D005796:Genes; D015235:HLA-B Antigens / Q000235:genetics; D059948:HLA-B44 Antigen; D006239:Haplotypes; D006801:Humans; D007564:Japan; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation; D012150:Polymorphism, Restriction Fragment Length; D013255:Steroid 21-Hydroxylase / Q000235:genetics*; D013250:Steroid Hydroxylases / Q000235:genetics*
chemical_list: D015235:HLA-B Antigens; D059948:HLA-B44 Antigen; D013250:Steroid Hydroxylases; D013255:Steroid 21-Hydroxylase