A MICROSATELLITE-BASED MHC GENOTYPING SYSTEM FOR HOUSE MICE (MUS-DOMESTICUS)

Major histocompatibility complex (MHC) genes are the most polymorphic loci known for vertebrates. Although this has been known for over two decades, the selective forces maintaining this genetic diversity are u nclear. Efforts to study selection on these loci in nature have been h ampered because no simple MHC typing systems are available. Here, we d escribe and evaluate a microsatellite-based MHC genotyping system for house mice (Mus domesticus). Thirty-five MHC-linked microsatellite loc i were tested for amplification and scoring reliability, and 21 were d eemed useful. These 21 loci were efficient at discriminating among nin e serologically distinct MHC haplotypes, with 52 % of microsatellite p airs providing 100% resolution. Since these microsatellite loci are sc attered across the entire MHC region, they will be effective at detect ing recombinant haplotypes. The number of alleles is higher for micros atellites inside the MHC than outside it, which presumably reflects ge neric hitchhiking with MHC alleles under balancing selection. This mic rosatellite typing system now allows testing hypotheses about the natu re of selection operating on MHC genes in natural populations of M. do mesticus and other murid rodent species.