LINKAGE RELATIONSHIP OF C2 DEFICIENCY, HLA AND GLYOXALASE-I LOCI

Abstract. Immunogenetic analysis of a homozygous C2‐deficient individual and family members demonstrated linkage of HLA‐A25, B18 and C2°. HLA‐D typing showed that 5 members typed with homozygous Dw2 typing cells from an individual with C2 deficiency but not with Dw2 typing cells from 2 individuals with normal C2. The homozygous C2‐deficient propositus and brother were HLA‐A and B homozygous but heterozygous at the HLA‐D and glyoxalase I loci. Therefore, in this family, the C2° gene is linked with two distinct haplotypes: HLA‐A25, B18, Dw2, GLO1 and HLA‐A25, B18, D unknown, GL02. These results could be explained by an ancestral recombinant event, which occurred between the C2° locus and HLA‐D locus in which C2° segregated with HLA‐B. This would suggest that the locus for the C2° gene maps between HLA‐B and HLA‐D on the sixth chromosome. © 1979 Blackwell Publishing Ltd