HLA-DRB1 and Autoimmunity: A study by Larizza et al. [26], which found a significant association between H. pylori infection and AITD, mostly in the presence of the HLA-DRB1*0301 allele—a well-known marker of autoimmunity—underlines the crucial role of a predisposing host genetic makeup in triggering and maintaining autoimmunity.