HLA-DRB1 and autoimmune disease: Increased susceptibility to T1D is given by environmental (body mass index, nutrition habits, total weight, etc.)and genetic factors (55), the latter sustained by the comorbidity in T1D patients with other autoimmune diseases (e.g. CD) and the association with certain HLA class II haplotypes, such as HLA-DRB1, HLA-DQA1, and HLA-DQB1 (56).