New polymorphism in the 5′ flanking region of IGF-1 gene and its association with wool traits in Egyptian Barki sheep

Insulin-like growth factor-1 gene (IGF-1) is considered as a major candidate gene for the economic traits of animal production. Polymorphism of 5′ flanking region of IGF-1 gene in Barki sheep (n = 91) and its association with wool traits were studied using the polymerase chain reaction coupled with single-strand conformation polymorphism technique (PCR-SSCP), PCR-restriction fragment length polymorphism (PCR-RFLP), sequence analysis and different measurements of wool traits (clean fleece weight and fiber diameter). PCR-SSCP analysis revealed three different banding patterns corresponding with three genotypes frequencies GG (0.25), GA (0.58), AA (0.17). PCR-RFLP and corresponding sequence analysis revealed nucleotide transversion from Guanine (G) to Cytosine (C) at nucleotide position 85 and transition from (G) to Adenine (A) at position 87. This is the first study that recorded two SNPs within the 5′ flanking region of IGF-1 gene in Egyptian Barki sheep, which were submitted to DNA Data Bank OF Japan (DDBJ) with Accession No. LC151463.1. The genotype GG showed positive significant association (P < 0.001) with clean fleece weight (CFW) trait (Odd Ratio = 2.83). By contrast, genotype AA had negative significant association (P < 0.05) with such trait (Odd Ratio = 0.15). On the other hand, fiber diameter (FD) measurements showed no significant association (P > 0.05) with different IGF-1 genotypes. This study adds evidence of the association between IGF-1 gene polymorphism and CFW of wool in Egyptian Barki sheep. Therefore; it is important to consider IGF-1 gene as a candidate gene marker for wool weight traits and it should be identified before using successful breeding program.