Association between IgH enhancer hs1.2 and type 1 diabetes

Aim: To investigate the association of alleles of the 3′ immunoglobulin heavy-chain regulatory region 1 (3′RR-1) enhancer hs1.2 in patients with type 1 diabetes (T1D). Methods: Eighty-one patients with T1D [among which 12 had concomitant coeliac disease (CD) and 25 an autoimmune thyroid disease (AITD)] were compared to 248 healthy individuals. All subjects were recruited from the same geographical area. Blood samples were collected from all patients and a nested PCR was performed to amplify the core of the 3′RR-1 and detect the alleles of the hs1.2 enhancer. Results: Allele distribution in healthy individuals was significantly different when compared to that of patients with T1D (p < 0.01). Even greater differences were detected comparing allele distribution of patients with T1D alone versus those with concomitant CD, but not versus those with concomitant AITD. The frequency of *2 allele is increased by 23% in patients with T1D and CD. Conclusions: The present study establishes that the multiallelic hs1.2 enhancer of the 3′RR-1 is associated with T1D, with higher frequency when there is co-occurrence of CD. This evidence has been previously observed in other immune diseases.