HLA-G and rheumatoid arthritis: This hypothesis is further supported by frequent HLA-G association with other autoimmune diseases, such as lupus erythematosus systemic [49,50], Crohn’s disease [51,52], multiple sclerosis [53,54], rheumatoid arthritis [55,56], and pemphigus vulgaris [57], along with HLA-G ectopic expression in skin pathologies [58,59].