Genome-wide association study (GWAS) with productivity in Romanov sheep breed

Genetic technologies used in breeding of small ruminants requires searching for new molecular markers of productive traits. The most effective for this is genome-wide association study (GWAS) of single nucleotide polymorphisms (SNP) with economically valuable traits. The paper presents results of study of associations of the frequency of single nucleotide polymorphisms with a rank assessment according to complex of productive traits (super-elite) in Romanov sheep using DNA biochips Ovine Infinium HD BeadChip 600K. Eleven SNPs have been found having significant correlation with the animals belonging to the “super-elite” group. Five substitutions are located in the genes introns, six are related to intergenic polymorphisms. The highest reliability of association with productivity was observed in substitution rs410516628 (р = 3,14 · 10-9) located on the 3rd chromosome. Substitution rs422028000 on 2nd chromosome differs with the fact that in the “super-elite” group it was found in 90 % of haplotypes. Polymorphisms rs411162754 (1st chromosome) and rs417281100 (10th chromosome) in our study turned out to be the rarest – only in “super-elite” group and only in a quarter of haplotypes. The genes located near the identified SNPs are mainly associated with metabolic and regulatory processes. Our study has identified several new candidate genes with polymorphism probably associated with the ranking in terms of productivity in Romanov sheep: LTBP1, KCNH8, LMX1B, ZBTB43, MSRA, CHPF, PID1 and DNER. The results obtained create a theoretical basis for further study of candidate genes affecting implementation of phenotypic traits in Romanov sheep. The revealed polymorphisms associated with the productive traits of sheep can be used in practical breeding as molecular and genetic markers for selection of parental pairs.