HLA-DQ region RFLPs indicate that susceptibility to insulin dependent diabetes in South India is located in the HLA-DQ region

Abstract

Recently close markers for insulin-dependent diabetes mellitus in Western 'Caucasoid' subjects have been defined from DQ region (both and β genes) restriction fragment length polymorphisms. In order to define the genetic contribution to insulin-dependent diabetes mellitus in an Indian population we have analysed 58 unrelated Dravidian (South Indian) insulin-dependent diabetic patients and 43 controls. In insulin-dependent diabetes an increased frequency of the Taq 1 DQβ restriction fragment length polymorphisms designated T2Ω/T6 (relative risk = 10.6), and of homozygotes for Taq 1 DQα 4.6 kb (relative risk = 11), was found in the patients. The highest relative risk for insulin-dependent diabetes mellitus was obtained by comparing patients and control subjects who either (a) co-inherited DQT2Ω/T6 with certain DQ restriction fragment length polymorphisms or (b) were DQα 4.6 kb homozygotes, the combination of (a) and (b) accounting for 55.5% of insulin-dependent diabetes mellitus subjects and none of the controls (relative risk = 101; 95% confidence limits 93-109).