The human Major histocompatibility (MH) genes are localized in the major histocompatibility complex (MHC) locus that is located on the short arm of the chromosome 6 at 6p21.3. The chromosome 6 is estimated to be 150-180 Mb in size. The MHC locus spans about 4Mb.
From HLA-F (telomeric in the MHC locus) to TAPBP (TAPASIN) (centromeric in the MHC locus), the MHC locus contains at least 121 functional genes and, among them, all the MH class I or MH1 genes (in the telomeric part of the locus or MHC-I) and MH class II or MH2 genes (in the centromeric part of the locus or MHC-II). MH1 and MH2 genes comprise 'classical' and 'nonclassical' genes . Ib indicates that HLA-F and HLA-G are nonclassical MH1. The central part of the locus or MHC-III contains genes other than MH, encoding related proteins of the immune system, and among them RPI-MH1Like genes (MICA, MICB), genes involved in the antigen processing, and cytokines.
 Lefranc, M.-P. et al., Dev. Comp. Immunol., 29, 917-938 (2005). PMID: 15936075 with permission from Elsevier