Exploring IGF-1 Gene Polymorphisms in Diverse Saudi Arabian Dromedary Camel Breeds

The insulin-like growth factor 1 (IGF-1) gene plays a key role in growth and production traits in livestock. Limited information is available regarding its genetic polymorphisms in Saudi camel breeds. This study aimed to investigate genetic variation in the IGF-1 gene among Saudi camel breeds to provide baseline genetic information for future association studies. A total of 176 camels representing six Saudi breeds were sampled. DNA was extracted and Polymerase chain reaction (PCR) amplification and Sanger sequencing were applied to detect IGF-1 polymorphisms. Genotype and allele frequencies were calculated across breeds, and statistical comparisons were performed based on proportional distributions to account for unequal sample sizes. Two single-nucleotide polymorphisms (SNPs) were identified: c.365G>A in exon 3 and c.435C>T in exon 5. The exon 3 variant resulted in a missense mutation (p. Arg122His) but was detected in heterozygous form in only one camel, and subsequent screening of 109 additional samples confirmed its rarity. The exon 5 variant was synonymous in isoform X1 and located in the 3′ untranslated region of isoform X2. Sequencing of 176 camels revealed that c.435C>T was highly polymorphic across the examined breeds. Significant differences in genotype frequencies were observed within and among breeds (p < 0.001). The CT genotype predominated in Waddah (60%), Shageh (48%), and Sofor (60%), significantly exceeding CC and TT frequencies (p < 0.001). In Majaheem and Saheli, CT (47%) and TT (45%) were nearly equal and both significantly higher than CC (p < 0.001). Shaele exhibited a distinct pattern, with TT being most frequent (57%), significantly higher than CC (7%, p < 0.001) and CT (36%, p < 0.01). These findings indicate directional selection favoring the C allele in the Waddah and Shageh breeds, whereas the T allele is favored in the remaining breeds. This study provides the first baseline characterization of IGF-1 polymorphisms among Saudi camel breeds. Although no phenotypic associations were assessed, the results offer a foundation for future research examining relationships between IGF-1 variants and economically important traits.