Genetic polymorphisms in part of intron 7 and exon 8 of HSP90AA1 gene and its association with heat tolerance traits in two exotic layer chicken strains

Chickens, like other vertebrates, react to stress conditions through their cultured cells by expressing heat shock proteins (HSPs). Genetic association of single-nucleotide polymorphisms (SNPs) in HSPs with desirable traits will reveal their importance as potential genetic markers. Blood samples were collected from 50 birds per strain for DNA extraction, polymerase chain reaction amplification and sequencing of the HSP90AA1 gene. SNPs were detected using Codoncode Aligner. Association of each SNP with heat tolerance traits was analysed using generalized linear model procedure of SAS. A total of seven SNPs were detected, four SNPs; A7T, A160T, T223A and C134T were detected in part of intron 7 to exon 8 of HSP90AA1 gene of BRD while three A160T, T223A and C134T were detected in HYL. SNPC134T, a synonymous variant, was detected in exon 8. Only SNPA7T was in Hardy-Weinberg equilibrium (X² = 0.03) but had no association with the traits measured. Polymorphic information content calculated showed SNPA160T to be moderately polymorphic; other SNPs were lowly polymorphic. Heterozygosity for SNPs-A160T and T223A of BRD showed moderate genetic variation while the other SNPs and those in HYL recorded low genetic variation. The study concluded that the SNPs detected were majorly lowly polymorphic and also the SNP locus A7T in intron 7 of HSP90AA1 of BRD had no genetic association with heat tolerance traits.