DRB1*04 and DQB1*03 Alleles are Very Prevalent in Bahraini Families with Both T2DM and T1DM

Objectives: Several investigations in families with both T1DM and T2DM have been reported to elucidate the genetic interaction between T1DM and T2DM and the clinical consequences for both diseases. The frequent occurrence of T1DM in relatives of patients with T2DM has also been previously observed. This study investigated whether the T2DM parent/grandparents share a specific HLA class II-DRB1and DQB1 alleles and their haplotype combination with the T1DM child. Methods: Twenty four Bahraini families with a T1DM child and either parents or grandparents with T2DM and with no family history of T1DM were selected. HLA class II-DRB1 and DQB1 were examined by SSP-PCR method and the distribution was analyzed. Results: In relation to DRB1*, the most common shared allele was DRB1*04:01:01 83% (n=20), while the most common shared DQB1* allele was DQB1*03:02:01 83% (n=20). In addition, the most common shared haplotype was DRB1*04:01:01-DQB1*03:02:01 83% (n=20). Conclusions: The current study showed that DR4 and DQ3 alleles and its haplotype combination are the highest prevalence in the selected Bahraini families with mixed T1DM and T2DM patients. T2DM parents possessing this haplotype are more likely to have a child with T1DM, especially in families with no history of T1DM. The excess transmission of DR4-linked haplotypes from parents with T2DM to offspring with T1DM has been clearly observed in the present study.