Identification of allelic variants of complement C4-A and Lactoferrin genes using iPLEX technique and its association with somatic cell count in Holstein cattle

The aim of this study was to identify the allelic variants of C4-A and LF genes and to investigate their associations with the nunber of milk somatic cells in Holstein cows. Mastitis is one of the most common diseases in dairy cows, that reduces milk production and imposes high costs on breeders. C4-A and lactoferrin genes are amonge the genes that affect the immune system to fight pathogens, microbial agents and mastitis. 384 blood samples were prepared from Holstein cows and DNA extraction was performed using optimized salting out method. IPLEX technique was used to determine the genotype of the samples. To identify single nucleotide polymorphisms, the marker sites of 1-rs137485678; C<G and 2-rs132741478; C<T for C4- A complement gene and 1-rs384176726; A<G and 2-rs445918028; A<T were selected for the LF gene. Genotyping at 1-rs137485678; C<G locus of C4-A gene showed two C and G alleles with frequencies of 58 and 42 %, and also three genotypes CC, CG and GG with frequencies of 31, 53 and 16%, respectively. No polymorphisms were observed at the other sites. Marker-trait analysis showed a statistically significant association (P<0.05), so that cows with CG genotype had the lowest number of somatic cells. Phase software was used to identify haplotypes. Based on the results of this research, the marker rs137485678; C <G-1 of the C4-A gene can be used as a genetic marker to improve mastitis in dairy cows.