title: Genetic mapping of the 21-hydroxylase locus: estimation of small recombination frequencies.
abstract: The locus for 21-hydroxylase (CA21HB) has been mapped to the interval between the HLA-B and HLA-DR loci on chromosome 6. Several methods of estimating genetic distance were used to determine whether CA21HB is closer to HLA-B or HLA-DR based on data collected on 157 families ascertained through a proband with the classical form of 21-hydroxylase deficiency (CA12Hd). The results were inconclusive but serve to highlight the limitations of present methods of estimating genetic distance when recombination frequencies are of the order of .005.
mesh_terms: D002874:Chromosome Mapping; D002896:Chromosomes, Human, Pair 6; D003181:Complement C4 / Q000235:genetics; D015935:Complement C4b; D005805:Genes, MHC Class I; D005802:Genes, MHC Class II; D008040:Genetic Linkage; D006680:HLA Antigens / Q000235:genetics; D006684:HLA-DR Antigens / Q000235:genetics; D006239:Haplotypes; D006801:Humans; D011995:Recombination, Genetic; D013255:Steroid 21-Hydroxylase / Q000235:genetics*; D013250:Steroid Hydroxylases / Q000235:genetics*
chemical_list: D003181:Complement C4; D006680:HLA Antigens; D006684:HLA-DR Antigens; D015935:Complement C4b; D013250:Steroid Hydroxylases; D013255:Steroid 21-Hydroxylase