Evaluation of insulin-like growth factor-I gene polymorphism in Egyptian small ruminant breeds

The genetic improvement of production traits can be developed through marker assisted selection. Insulin-like growth factor I ( IGF -I) is a member of the somatotrophic axis which has a remarkable variation of its biological effect including protein synthesis and skeletal growth. This study aimed to detect the genetic polymorphism of IGF -1 in different Egyptian sheep and goat breeds. The amplified fragments at 320-bp were digested with HaeIII endonuclease and the results show the presence of three different genotypes: CC (15.71%), CG (29.29%) and GG (55.0%). The nucleotide sequence analysis of C and G alleles declared the presence of a single nucleotide polymorphism (C→G) at position 282. The nucleotide sequences of alleles C and G in sheep and goat were submitted to GenBank with the accession number: KX432965, KX432966, KX432967 and KX432968, respectively. In conclusion, a nucleotide substitution (C→G) was detected in IGF -I gene in Egyptian sheep and goat breeds resulting in the presence of three different genotypes; CC, CG and GG. The association of IGF -I polymorphism with different growth trait parameters were reported at significant levels, so, the genetic and SNP variations in IGF -I gene may be a potential molecular marker for growth traits in different Egyptian sheep and goat breeds. Keywords: IGF -1, polymerase chain reaction - restriction fragment length polymorphism (PCR-RFLP), DNA sequencing, sheep, goat