The MHC, disease, and immune function. The MHC shows associations with almost all known autoimmune diseases as well as many inflammatory and infectious diseases. Major disease associations are listed by trait. Recent high-resolution SNP typing has defined specific SNP markers in some instances, but associations defined by HLA type remain robust; examples of top associations are shown. Extensive linkage disequilibrium has made fine mapping such associations challenging. In some instances, associated haplotypes span several megabases of the classical MHC. Examples of the role of MHC genes in immune function are illustrated, including the key role in antigen presentation and processing as well as inflammation, the complement cascade, and stress response (51). The tapasin-encoding gene (TAPBP), which is involved in peptide loading onto MHC class I and in the association of MHC class I with TAP, is not shown here but is just outside the class II region shown.