The profile of HLA-DRB1 alleles in Arabs with type 1 diabetes; meta-analyses

Genes from the HLA complex have a major contribution in type 1 diabetes (T1D), which results from an interplay between environmental and genetic factors. The latter can explain some of the geographic variability in T1D occurrence around the world. Of a particular importance in this regard are the HLA-DR, -DP and -DQ loci. Consequently, we aimed at elucidating the collective genetic profiles of various alleles relating to HLA-DRB1 and -DP in T1D patients throughout the Arab World using the tools of meta-analysis. As for HLA-DQA1 and DQB1 alleles; this analysis was completed and published previously (see Introduction). As a result of limited availability of relevant studies of the HLA-DP locus, only HLA-DRB1 alleles were tackled in this paper. Our study showed that significant increases in T1D risk resulted from harboring the alleles DRB1*03:01 and *04:05 (odds ratio 7.76 and 7.52, respectively). DRB1*04:01 and *04:02 were also predisposing for T1D in Arabs. Very strong evidence supported the protective effects of DRB1*10:01, *13:01, *15:02 and *16:01, with low heterogeneity and no publication bias. The results from the series of meta-analyses performed in this study help to complete the global genetic epidemiological map of T1D by providing statistically robust data from the Arab World.