KRTAP27-1 (keratin-associated protein 27-1) is a hair follicle-specific protein that functions in hair shaft structure formation. As part of the keratin-associated protein family, KRTAP27-1 contributes to the interfilamentous matrix surrounding hair keratin intermediate filaments, stabilizing hair structure through extensive disulfide bond cross-linking with cysteine-rich hair keratins 1. The protein is predominantly expressed in skin tissue, particularly in hair follicles, with expression patterns similar to other KAP family members 1. In caprine (goat) models, KRTAP27-1 genetic variation directly influences fiber diameter traits; specifically, a nonsynonymous SNP (c.413C/T; p.Ala138Val) and synonymous SNP (c.495C/T) correlate with cashmere fiber diameter, with the B variant associated with increased mean fiber diameter 1. These findings parallel observations in sheep wool, where related KRTAP genes regulate fiber diameter uniformity 2. A germline KRTAP27-1 variant (rs2244485) has been identified in genomic studies of hereditary colorectal cancer patients, though its specific pathogenic mechanism remains unclear and requires further validation 3. The primary established function remains hair fiber structure and quality, making KRTAP27-1 clinically relevant for wool and fiber production improvement.