Izaabel H, Garchon H J, Beaurain G, Biga M, Akhayat O, Bach J F, Caillat-Zucman S
INSERM U25, Hopital Necker, Paris, France.
Hum Immunol. 1996 Sep 1;49(2):137-43. doi: 10.1016/0198-8859(96)00104-8.
HLA class II polymorphism in Moroccan IDDM patients has not been investigated so far. In this study, HLA-DRB1, -DQA1, and -DQB1 allele and haplotype frequencies were analyzed in 125 unrelated Moroccan IDDM patients and 93 unrelated healthy controls, all originating from the Souss region and mostly of Berber origin. Some common features with other Caucasian groups were observed, in particular, a predisposing effect of the DRB103-DQA10501-DQB10201 and DRB104-DQA10301-DQB10302 alleles or allelic combinations. The Moroccan IDDM group also presented with more specific characteristics. Among DRB104 subtypes, DRB10405 was associated with susceptibility to and DRB10406 with protection from the disease. The haplotype and the relative predispositional effect (RPE) analyses indicated that the DRB108-DQA10401-DQB10402 haplotype was also associated with susceptibility to IDDM. Interestingly, the DRB109-DQA10301-DQB10201 haplotype, completely absent from the control group and very rare in North African populations, was observed in 7.2% of the Moroccan diabetics. Conversely, the DRB107-DQA10201-DQB10201 and DRB115-DQA10102-DQB1*0602 haplotypes were associated with protection from IDDM. Finally, we observed an age-dependent genetic heterogeneity of IDDM, the frequencies of predisposing alleles being higher and those of protective alleles lower in childhood- than in adult-onset diabetics. Our data on Moroccan diabetics, together with data on European and Northern Mediterranean patients, suggest a gradient of various HLA class II predisposing and protective markers that link these populations.
