We investigated on the mechanism causing the differential expression of HLA genes associated with T1D and CD risk by nucleofection of the full-length DQA1*05 or DQB1*02 cDNA (pDQA105 and pDQB102) and the DQA1*05 deleted of 3′UTR (pDQA105Δ) cDNA in DR1/DR3 B-LCL#5. This evidence concerns the gene HLA-DQA1 and type 1 diabetes mellitus.