Molecular genetic monitoring of hereditary abnormalities in cattle: hypotrichosis, idiopathic epilepsy and dilutor phenotype (review)

The article describes the urgent problem of reducing reproductive function in cattle of the Hereford and Kazakh white-headed breeds, which has a significant impact on the economic performance of animal husbandry. The main attention is paid to three key genetic disorders: hypotrichosis (HY), idiopathic epilepsy (IE) and dilutor phenotype (DL), which significantly reduce productivity and reproductive abilities of animals. The materials discuss in detail the molecular and genetic mechanisms of each of the disorders. Key genes (MC1R, PMEL, KRT71) responsible for the development of the coat have been identified for hypotrichosis. In the case of idiopathic epilepsy, the focus is on mutations in the DYRK1B gene that affect neurological functions. The dilutor phenotype, which manifests itself in a decrease in pigmentation, is mainly associated with the PMEL mutation (p.Leu18del). It has been established that hypotrichosis associated with mutations in the KRT71 and LYN genes has a low prevalence in Russian Aberdeen-Angus populations (0.02%), but a high prevalence in Uruguayan Herefords (41.2%). There is no data on the prevalence of IE in Herefords and Kazakh white-headed breeds. Dilutor-phenotype, associated mainly with mutations in the PMEL gene, was identified in Hereford cattle. It has been established that this genetic disorder has a pleiotropic effect, improving the quality of meat, but increasing the sensitivity of animals to solar radiation. Modern methods of genomic analysis (PCR, sequencing, GWAS) allow for the effective detection of carriers of abnormalities. A promising approach is the use of genomic editing (CRISPR-Cas9) to create climate-adapted cattle lines without compromising productivity. The development of genetic monitoring and selection systems based on DNA testing is necessary to minimize economic losses and increase the efficiency of breeding work. Special attention is paid to the need to control imported breeding material and develop strategies for managing genetic risks.

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