Association of two SNPs in the coding region of the insulin-like growth factor 1 receptor (IGF1R) gene with growth-related traits in Angus cattle.

The insulin-like growth factor 1 (IGF-1) is considered to be a factor that mainly regulates growth, differentiation, and the maintenance of various function in numerous tissues through binding to a family of transmembrane tyrosine kinase receptors, signaling primarily through the insulin-like growth factor 1 receptor (IGF-1R) encoded by the IGF1R gene. The objectives of the present study were to estimate the allele and genotype frequencies of the IGF1R/MspI (silent mutation within exon 12) and the IGF1R/TaqI (within the 3' untranslated region, 3'UTR) gene polymorphisms in beef cattle and to determine associations between these polymorphisms and growth traits. In a preliminary study on 310 Angus calves, association analyses with three production traits (birth weight, BWT; weaning weight adjusted to 210 days, WWT210; and average daily gain, ADG) were conducted. The GG genotype of the IGF1R/e12/MspI polymorphism was significantly associated (P ≤ 0.05) with a higher WWT210 (+5.06 kg) compared to the AG genotype. Polymorphism within the 3'UTR had no significant effect on growth traits. The effect of combined genotypes was also examined. At WWT(210), calves with the GG/AA and GG/AG combinations were heavier than calves with the AG/AA and AG/AG combined genotypes (P ≤ 0.05). To our knowledge, this is the first report of a polymorphism within the coding region of the Bos taurus IGF1R gene.