Evidence for absence of linkage between the B and Z as well as between the F and S systems of cattle blood groups

The bovine B and C blood group systems are not likely to be the orthologues of human RH: an interesting twist in the comparative map

We tested the hypothesis that either the bovine B or C blood group system is the orthologue of human RH. A comparative linkage mapping strategy was applied, using blood typing and restriction fragment length polymorphism (RFLP) analysis of four loci linked to RH on HSA1; PGD, FGR, ALPL and FUCA1. Four sires with a total of 255 half-sib offspring were used for the linkage analysis. Strong support for linkage between ALPL, FUCA1 and FGR was obtained for all sire families (lod scores > 11 for all pairwise comparisons). This new linkage group was assigned to bovine synteny group U17 based on previous somatic cell mapping of the FGR locus. The most favoured order is ALPL-FUCA1-FGR (2.18:1), with ALPL and FGR 5.4 CM and 6.3 CM, respectively, from FUCA1. The B and C blood group systems and PGD were genetically independent of each other and all other markers, indicating that neither B nor C is likely to be the bovine orthologue of human RH. However, given available comparative mapping data, there is some chance that the bovine orthologue of RH is on bovine synteny group U6. Although gene order appears to be conserved with humans, the differences in recombination rates between these three loci in cattle, humans and mice strongly suggest that it is not possible to use human map distances to predict map distances in cattle, making it imperative that bovine gene mappers continue to emphasize adding type I markers to the bovine linkage map.

Linkage of bovine erythrocyte antigen loci B, C, L, S, Z, R' and T' and the serum protein loci post-transferrin 2 (PTF 2), vitamin D binding protein (GC) and albumin (ALB) to DNA microsatellite markers

Seven bovine erythrocyte antigen loci and three serum protein loci were tentatively assigned to chromosomes or synteny groups by linkage analysis to previously assigned microsatellite DNA markers. The erythrocyte antigen locus EAB was mapped to synteny group U27; EAC to chromosome 18, synteny group U9; EAL to chromosome 3, synteny group U6; EAS to chromosome 21, synteny group U4; EAZ to chromosome 10, synteny group U5; EAR' to chromosome 16, synteny group U1; and EAT' to chromosome 19, synteny group U21. The vitamin D binding protein (GC) and albumin (ALB) loci were assigned to chromosome 6, synteny group U15 and post-transferrin 2 (PTF 2) to chromosome 19, synteny group U21.