Association of KRTAP24-1 Gene Polymorphisms with Wool Traits in Tibetan Sheep (Ovis aries)

KRTAP24-1 belongs to the high-sulphur KAP family and has been associated with cashmere fibre diameter in goats, but its role in ovine wool traits remains unclear. This study assessed KRTAP24-1 tissue expression by RT-qPCR and investigated genetic variation and associations with wool traits in 277 Tibetan sheep. Polymorphisms in the coding region were identified by PCR amplification and Sanger sequencing, and genotyping was performed using PARMS. A linear mixed model (LMM) incorporating a genomic relationship matrix (GRM) was used to evaluate associations between SNPs, haplotypes, and 12 wool traits. Bioinformatic analyses were restricted to the five haplotypes observed in the study population and were used as preliminary in silico assessments. Three missense SNPs were identified: c.191C>T (p.L64P), c.527G>A (p.G176D), and c.656C>T (p.A219V). The c.191C>T variant was associated with mean fibre length (MFL), single fibre tenacity (SFT), and scoured yield (SY), whereas c.656C>T was associated with lock length (LL) and clean fleece yield (CFY). Several haplotype combinations were also associated with LL, elongation at break (EB), and CFY. KRTAP24-1 showed high expression in skin. The observed haplotypes showed only minor differences in predicted mRNA secondary structure and mainly local changes in predicted protein features. These findings suggest that KRTAP24-1 may provide a preliminary basis for marker-assisted selection in Tibetan sheep breeding, but its functional role requires further validation in independent populations and experimental systems.