IGF-1 Gene Polymorphisms Influence Bovine Growth Traits in Chinese Qinchuan Cattle.

Insulin-like growth factor I (IGF-1) influences gonadotrophin-releasing hormone (GnRH) neurons during puberty, and plays an important role in muscle growth in farm animals. The objective of this study was to estimate the genotype frequencies of the polymorphisms of IGF-1 and to determine associations between these polymorphisms and growth traits in Chinese Qinchuan cattle breeds. Five single nucleotide polymorphisms (SNPs), including one in intron 2 (g.5172T>G) and four in intron 3 (g.56495C>A, g.56501C>T, g.56801C>T and g.71090T>G) were identified according to the sequencing results of 487 individual of a Qinchuan cattle population. The chi-square test showed g.5172T>G, g.56495C>A and g.56801C>T were in Hardy-Weinberg equilibrium in all the samples. Six different haplotypes were identified, of which two major haplotypes had a frequency of 48.2% (-TCTTT-) and 16.3% (-TCCTT-). The single marker association analysis showed that the three polymorphisms (g.5172T>G, g.56501C>T and g.71090T>G) were significantly associated with growth traits (at P<0.01 or P<0.05). In conclusion, our results suggest that some polymorphisms in IGF-1 may play a role in determining one of the important genetic factors that influence growth traits in Chinese Qinchuan cattle. [ABSTRACT FROM AUTHOR]