novel snps of the abcg2 gene and their associations with milk production traits in iranian holstein bulls

abcg2 (atp binding cassette subfamily g member 2) gene, located on chromosome 6 encodes the abcg2 protein that transports various xenobiotics, cytostatic drugs across the plasma membrane as well as cholesterol into milk. a single nucleotide change (a/c) in base 86 of exon 14 is capable of encoding a substitution of tyrosine with serine in the abcg2 gene and increase milk yield while decreasing milk fat and protein concentrations. the major aim followed in this research was to study single nucleotide polymorphisms (snps) of abcg2 gene and their association with milk production traits in iranian holstein bulls. genomic dna of 105 ified bulls was extracted from semen samples using highly pure pcr template preparation kit. primers were designed through oligo software (version 5.0) and utilized in pcr. then the pcr fragments were sequenced. the a/c substitution in base number 86 of exon 14 was observed with 2% frequency which affected protein percentage (p< 0.05). some snps were detected for the first time in intron 13, exon and intron 14 in comparison with sequences in the ncbi database. a deletion mutation in base number 20 (t/-) and a missense mutation in base number 67 (a/g) of exon 14 that cause the substitution of serine with glycine were discovered which were significantly associated with protein yield and fat percentage, respectively (p< 0.05). furthermore, significant association was observed between fat percentage and mutations in base numbers 4,133 (t/c) and 4,137 (t/g) of intron 13 (p< 0.05). substitutions in base numbers 2 (t/c) and 55 (g/c) of intron 14 resulted in a significant effect on fat yield and fat percentage (p< 0.05).