Over the last decade, genome-wide association studies have consistently identified genes within the major histocompatibility complex (MHC), located on the short arm of chromosome 6, strong regulators of disease risk in a number of AI diseases such as multiple sclerosis (MS) (International Multiple Sclerosis Genetics Consortium et al., 2007, 2011; Patsopoulos et al., 2011), rheumatoid arthritis (RA) (Plenge et al., 2007; Raychaudhuri et al., 2008; Okada et al., 2012), and vitiligo (Jin et al., 2010; Quan et al., 2010). This evidence concerns the gene HLA-C and rheumatoid arthritis.