Linkage relationships between ALPL, ENO1, GPI, PGD, and TGFB1 on porcine chromosome 6

A five-point linkage map has been established between the loci encoding liver/bone/kidney alkaline phosphatase (ALPL), enolase 1-alpha (ENO1), glucose-phosphate isomerase (GPI), phosphogluconate dehydrogenase (PGD), and transforming growth factor beta 1 (TGFB1) in swine. Linkage analysis was performed using the Meishan x Yorkshire three-generation reference pedigree at the University of Illinois (n = 91). Previously ENO1, GPI, PGD, and TGFB1 were mapped to porcine chromosome 6q by in situ hybridization but the linkage relations of TGFB1 and ENO1 with other loci in this group were not investigated. Based on mapping data from human chromosomes 1 and 19 and mouse chromosomes 4 and 7, it was postulated that ALPL should reside among or near these loci. Restriction fragment length polymorphisms were identified for ALPL, ENO1, and TGFB1. GPI (EC 5.3.1.9) and PGD (EC 1.1.1.44) phenotypes were determined by agarose gel electrophoresis of isozymes. Marker data were analyzed using the MLINK (two locus) and ILINK (multilocus) programs from LINKAGE (version 5.10). The most likely locus order between GPI-TGFB1-(PGD-ENO1)-ALPL with recombination rates of 0.049, 0.044, 0.000, and 0.156, respectively, could not be significantly determined. The maximum five-point lod score was the same to four decimal places irrespective of the order of ENO1 and PGD. This indicates that ENO1 and PGD are very closely linked and that ALPL is located telomeric to the established linkage group on pig chromosome 6.