Single Nucleotide Polymorphisms in Insulin-like Growth Factor 2 (IGF2) gene and their associations with body weight and growth rate traits in indigenous guinea fowls (Numida meleagris) of northern Ghana

Abstract

Insulin-like Growth Factor 2 (IGF2) plays important roles in stimulating cell proliferation, differentiation and migration culminating its effects as a modulator of juvenile growth in animals. Although the gene that codes for IGF2 (IGF2) has been investigated as a candidate gene in several livestock species, there is no information on polymorphisms in IGF2 in guinea fowls (gIGF2), an important indigenous poultry species from West Africa. Therefore, this study sought to identify the Single Nucleotide Polymorphisms (SNPs) in three populations of indigenous guinea fowls in northern Ghana. Target genomic regions in gIGF2 were amplified and sequenced from 84 indigenous guinea fowls from Upper East Region (n = 17), former Northern Region (n = 22) and Upper West Region (n = 45) of Ghana together with domesticated French variety (n = 3). The sequences were aligned with the reference genomic sequence (domesticated French variety) of chromosome 6 (GenBank accession no., NC_034414.1) to identify SNPs. Statistical associations among the genotypes arising from the SNPs and juvenile growth traits were estimated using linear models. Two novel SNPs were identified in gIGF2 among the indigenous guinea fowls. An insertion of a Guanine (G) within a poly G motif of the intron following the third exon at the 13,955,730 bp location was identified in the majority (84.5%) of indigenous guinea fowls, while the wild type allele was observed in the minority of indigenous guinea fowls and in the domesticated French variety sampled. Also, a biallelic transition arising from the substitution of G by Adenine (A) at position 13,956,496 bp (13,956,496 G > A) located on the fourth exon, which codes for most of the extension peptide of prepro IGF2, was observed in the minority (11.9%) of indigenous guinea fowls. No significant associations among the genotypes arising from the two SNPs, with body weights and weekly growth rates, were identified.