Contribution of selective HLA-DRB1/DQB1 alleles and haplotypes to the genetic susceptibility of type 1 diabetes among Lebanese and Bahraini Arabs.

CONTEXT

Human leukocyte antigen (HLA) class II genes contribute to the genetic susceptibility of type 1 diabetes (T1D), and both susceptible and protective alleles were implicated with its pathogenesis, which varies among various ethnic/racial groups.

OBJECTIVE

This study investigated the heterogeneity in HLA class II haplotypes distribution among Bahraini and Lebanese T1D patients.

DESIGN

This was a cross-sectional retrospective study.

SETTING

The study was conducted at primary care private and public health centers.

PATIENTS AND OTHER PARTICIPANTS

Subjects comprised 126 T1D patients and 126 healthy controls from Bahrain and 78 Lebanese T1D patients and 111 control subjects.

INTERVENTION(S): There were no interventions.

RESULTS

Although Lebanese and Bahraini patients share DRB1030101, DQB10201 as susceptible and DRB1100101 and DQB1030101 as protective alleles, DRB1040101 was an additional susceptible allele in Bahraini patients, and DRB1130701 and DQB1050101 were additional susceptible and protective alleles in Lebanese, respectively. DRB1030101-DQB10201 was susceptible, whereas DRB1070101-DQB10201 and DRB1110101-DQB1030101 were protective haplotypes in Bahraini and Lebanese. DRB1040101-DQB10302 and DRB1040101-DQB1050101 displayed different associations: they were protective in Lebanese but susceptible or neutral among Bahrainis. Whereas the frequency of homozygous DRB103011-DQB10201 was higher in Bahraini and to a lesser extent Lebanese patients, homozygous DRB1110101-DQB1030101 was significantly more frequent in Lebanese but not Bahraini controls, whereas DRB1030101-DQB10201/DRB1040101-DQB1*0201 was the major genotype among Bahraini patients but not Lebanese subjects in whom it was present at very low frequencies.

CONCLUSION

In view of these differences between Bahraini and Lebanese, this demonstrates that the contribution of HLA class II to the genetic susceptibility to T1D must be evaluated with regard to specific HLA haplotypes and also ethnic origin and racial background.