Connections between the gut microbiome and general autoimmunity have been made by studies investigating the role of human leukocyte antigen (HLA) gene polymorphisms in autoimmunity risk in a number of diseases including type 1 diabetes (Jerram and Leslie, 2017), spondyloarthritis (Kopplin et al., 2016), Behcet’s disease (Ohno et al., 1982), and Celiac disease (Karell et al., 2003) explained through the impact of HLA on the amino acid sequence in class II major histocompatibility complex (MHC). The gene discussed is HLA-C; the disease is Behcet disease.