The bovine kappa-casein (CASK) gene is considered a potential marker for quantitative trait loci (QTL) in dairy cattle.A large amount of research has been performed to explore the nature and variation of the CASK gene and its possible applications in cattle breeding.The purpose of this review is to sum up the knowledge of all known aspects of the CASK gene; molecular structure and function, poltmorphism and allele frequency, methods of genotyping and possibilities of the use of CASK polymorphism in dairy cattle breeding.
The polymorphism of kappa-casein (alleles A, B and E) and growth hormone (alleles L and V) genes was studied using PCR/RFLP method with the aim to evaluate the degree of genetic diversity of Polish Red and German Red cattle, which are endangered with extinction. At the kappa-casein locus, a very low frequency of allele B in German Red cattle was found. In both the breeds, allele E was absent. There was a relatively high frequency of allele L in the growth hormone locus, especially for German Red cattle. The results were compared with frequencies and diversities of other red cattle breeds.