Good copy, bad copy: choosing animal models for HLA-linked diseases

Recent large-scale sequencing and comparative analyses of the major histocompatibility complex (Mhc) provide a novel view of this long-studied region. The main insight is that even though Mhcs are defined by the presence of the Mhc class I and II genes, the regions encoding class I/II histocompatibility antigens are the least conserved among the species; hence the difficulty of modeling the human class I/II-linked diseases. Fortunately, the majority of the genes in the Mhc, the non-class I/II genes, are conserved among the investigated mammals. The full set of Mhc genes in their evolutionary context presents new possibilities to study Mhc-linked diseases by allowing systematic evaluation of the various experimental animals and approaches.