A large linkage group on pig chromosome 7 including the MHC class I, class II (DQB), and class III (TNFB) genes

A three-generation reference family of wild x domestic pig has been typed for class I, class II (DQB), and class III (TNFB) genes of the major histocompatibility complex (MHC). The linkage relationships were examined between these loci and nine other markers on chromosome 7; the erythrocyte antigen J locus (EAJ), the peptidase N locus (PEPN), three tightly linked alpha -protease inhibitor (PI) loci (protease inhibitor-1, PI1; protease inhibitor-2, PI2; and postalbumin-1A, PO1A), and four anonymous microsatellite loci (S0064, S0066, S0101, and S0102). Linkage analysis revealed that the 12 loci formed a large linkage group. The results confirm that the pig MHC has the same principal organization and chromosomal orientation as has the human MHC, i.e., class I - class III - class II, with the class II loci oriented towards the centromere.