Abstract
By means of isoimmunizations and heteroimmunizations 10 equine blood typing reagents were isolated. The specific antibodies were complete agglutinins, which were used in the direct agglutination test in saline medium. The reagents were designated A(2), C, D, E, G, H, I, K, Da(1), and Da(2) reagent. Da(1) and Da(2) are preliminary designations. The data obtained from blood typing of a family material and a population material of Icelandic horses showed that the occurrence of each blood type factor is controlled by a single, dominant gene. The family data tended to show that the blood factors under investigation belonged to 8 blood type systems. The A system contained the antigens A(2) and Da(2). These antigens are related to each other through a linear subgroup relationship. The D system had the factors D and J. The G, E, G, I, K, and Da(1) systems are one-factor, two-allele blood type systems. The H factor was not observed in Icelandic horses. In connection with the establishment of the 8 blood type systems it must be emphasized that the problem of allelism or nonallelism of 2 genes can only be solved by means of relevant family data. Because of the rare occurrence of some of the blood factors in the Icelandic horse such data were in some cases not available. Thus some conclusions were based on results from two-by-two contingency tables with the use of population data. This was used particularly for the D and G systems, and additional family data are necessary for a definite establishment of these systems. Exceptions to the genetic theory, apparently caused by erroneous registration, were presented. Finally, estimates were given of gene frequencies of the causative genes among Icelandic horses. Starch gel electrophoresis of sera from Icelandic horses revealed the existence of 21 transferrin phenotypes. The data obtained supported the theory advanced, that transferrin polymorphism in horses is controlled by 6 autosomal codominant alleles: Tf(D), Tf(F), Tf(H), Tf(M), Tf(O), and Tf(H). 925 randomly selected Icelandic horses were typed for serum transferrin and the gene frequencies were estimated. Starch gel electrophoresis of about 100 horse serum samples did hot reveal individual variation of the equine haptoglobin and ceruloplasmin. Studies on approximately 300 sera showed an identical serum amylase pattern.