Comparison of HLA class II antigens between three type 1 diabetes groups in the central region of Algeria : research article

In human type 1 diabetes (T1D), both genetic and environmental factors are involved in the pathogenesis of the disease. The strongest genetic contribution has been mapped to the major histocompatibility complex (MHC) on the short arm of chromosome 6, which encodes the human leukocyte antigens (HLA). It is estimated that HLA class II gene polymorphisms account for 20 to 50% of familial aggregation of type 1 diabetes. Several studies have clearly demonstrated that there are susceptibility and protective markers at HLA-DR and -DQ. In this study, HLA class II antigens were investigated using a serological method in 210 T1D patients from the central region of Algeria, and compared to 140 healthy controls. Marker frequencies were compared between three groups of diabetics : children, juveniles and adults with latent autoimmune diabetes (LADA), and the control group. The frequency was calculated for HLA-DR and -DQ. Significant differences were detected between T1D patient and the control groups for the frequencies of HLA-DR3, -DR4, -DQ2 and -DQ8 (DQ3) but there were no significant differences in these antigen frequencies between the three T1D groups versus the controls, with the respective frequencies of HLA-DR3 (71.76, 66.67, 70% vs 31.43%), HLA-DR4 (64.71, 48.89, 52.50% vs 26.43%), HLA-DQ2 (76.47, 66.67, 75% vs 39.29%) and HLA-DQ8 (3) (64.71, 46.67, 47.50% vs 19.29%). Mantel-Haenszel tests were used to calculate the odds ratio for the presence of type 1 diabetes in association with HLA-DR3, -DR4, -DQ2 and -DQ8 (3). The values for each respective HLA antigen were as follows : for the T1D children (OR: 5.54; 5.1; 5.02; 7.67) for the juveniles (OR: 4.36; 2.66; 3.09; 3.66) and for LADA (OR: 5.09; 3.08; 4.64; 3.79). The heterozygous phenotype HLA-DR3/DR4 increased the risk (conferred the highest susceptibility) (OR: 8.79, 2.68, 4.23 for children, juveniles and the LADA group, respectively). These results confirm the positive association between T1D and HLA class II antigens, as previously reported in other populations in the central region of Algeria.