Linkage and interdependence of A2MD1 and A2ME2 alpha2-macroglobulin genes in cattle

The transmission of previously described genes A2MD1 and A2ME2 that determine antigenic markers of alpha₂-macroglobulins A₂mD1 and А₂mЕ2 in cattle was studied. The starting point for the analyses was the lack of individuals negative for both markers in the population of 3551 Black-and-White, Red-and-White, Polish Red and Simmental cattle and interbreed crosses. Controlling of these specificities by allelic genes or genes from closely linked loci was considered. To support or reject this hypothesis, the independence test 2 x 2 and analysis of segregation of A₂mD1 and А₂mЕ2 in the offsprings of all phenotypic matings found and of selected matings in which genotypes of sires were determined, were used. It was found that the observed segregation of antigenic markers in the offsprings rules out the possibility that they are determined by allelic genes. The results obtained show that markers A₂mD1 and А₂mЕ2 are controlled by the genes A2MD1 and A2ME2 from closely linked loci. Moreover it seems that only those haplotypes are transmitted in which both genes - A2MD1 and A2ME2, or one of them - A2MD1 or A2ME2, are present. No haplotypc would then be transmitted (would occur?) in which both genes are in the recessive form. recessive form.