HLA polymorphism in type 1 diabetes Tunisians.

Several studies of the association between HLA and type 1 diabetes have been carried out revealing differences between ethnic groups. Our study, as part of the studies that should be performed about this association in the rest of the word, aims at elucidating the HLA DRB1, DQB1 polymorphism in Tunisian type 1 diabetes. This study includes 43 unrelated type 1 diabetes patients, and their mean age at onset is less than 15 years. Analysis of the frequency of alleles and haplotypes in these subjects, compared to a reference group (n = 101) led to the following results. 1) The Tunisian insulin-dependent diabetics present similarities as well as differences with other ethnic groups (Caucasians, North Africans). 2) The haplotype DRB1*04 DQ*0302 and DRB1*03 DQB1*0201 is positively associated to type 1 diabetes. 3) The heterozygotic genotype DRB1*04 DQB1*0302 / DRB1*03 DQB1*0201 is strongly associated to type 1 diabetes. 4) The haplotypes DRB1*01501 DQB1*0602 and DRB1*11 DQB1*0301 proved to be protective. In addition, the study of the subtypes DRB1*04 showed that alleles DRB1*0405 predispose to type 1 diabetes, whereas the allele DRB1*0403, which is in linkage disequilibrium with the DQB1*0402 in the Tunisian population, has a protective effect.