HLA‐A3, B7 linkage disequilibrium in hemochromatotic patients with or without insulin dependent diabetes

Abstract

Idiopathic hemochromatotic French patients [66] were HLA-A,B typed. The previously known strong association with A3 was confirmed (RR = 10.6, P < 10-9); a gene implicated in idiopathic hemochromatosis (IH) determinism seems to be located in the HLA-A region. The linkage disequilibrium between A3 and B7 was far greater than in IH patients than in controls. This might be due to a selective advantage of this haplotype in IH. The A3, B7, Dw2 HLA haplotype was shown to exert a protective effect against common insulin dependent diabetes (IDD). The patients were divided into 2 groups according to the presence or absence of a definite IDD. B7 was found more frequently in IH patients without IDD but the difference is not significant. The strong linkage disequilibrium between A3 and B7 might be due to the protective effect of the B region of this haplotype against IH secondary IDD.