HLA-C and psoriasis: Polymorphisms expressed by the MHC genomic region influence many critical biological traits and individuals’ susceptibility to the development of chronic autoimmune diseases such as type I diabetes, rheumatoid arthritis, celiac disease, psoriasis, ankylosing spondylitis, multiple sclerosis, Graves’ disease, schizophrenia, bipolar disorder, inflammatory bowel disease, and dermatomyositis [2,6,7,8].