# The Identification of a New Gene KRTAP 6-3 in Capra hircus and Its Potential for the Diameter Improvement of Cashmere Fibers

## TL;DR

This study identifies a new gene, KRTAP6-3, in goats that may help improve the quality of cashmere fibers.

## Contribution

The discovery of KRTAP6-3 gene variation and its association with cashmere fiber diameter in goats.

## Key findings

- Six SNPs were identified in KRTAP6-3, including three in the coding region and two synonymous mutations.
- Allele C of KRTAP6-3 is associated with increased mean fiber diameter in cashmere goats.
- KRTAP6-3 mRNA is strongly expressed in follicles and hair papillae during the anagen phase.

## Abstract

Background: Cashmere is one of the important economic products of goats, and the KRTAP gene family, as an important family of regulatory genes in the growth process of cashmere fiber, largely affects the quality of cashmere. Methods: In this study, the KRTAP6-3 gene was identified and located on goat chromosome 1 using a goat genome homology search combined with a phylogenetic tree approach. The Longdong cashmere goat KRTAP6-3 gene variation and its effect on cashmere quality were explored by using the polymerase chain reaction single-stranded conformation polymorphism (PCR-SSCP) technique, in situ hybridization, and the allele presence/absence model. Results: The results identified a total of six SNPs in KRTAP6-3, three of which were located in the coding region and two of which were synonymous mutations, in addition to 45- bp deletion sequences detected in alleles C and F. Moreover, the KRTAP6-3 mRNA showed a strong expression signal in the cortical layer of the primary and secondary follicles in the inner root sheaths, as well as in the cells of the hair papillae and the matrices during the anagen phase, and signaling at the sites described above is attenuated during the telogen phase. The presence of allele C was associated with increased MFD (mean fiber diameter) (p < 0.01). The MFD of goats with allele C genotype (genotype AC) was significantly higher (p < 0.05) than that of goats without allele C genotype (genotypes AA and AB). Conclusions: This indicates that genetic variation in the KRTAP6-3 gene in goats is significantly associated with cashmere traits and can serve as a candidate gene for molecular markers of cashmere traits.