# Genome-Wide Association Study of Gross Hair Weight and Hair Length Traits in Different Body Regions of Tianzhu White Yak

## TL;DR

This study identifies genetic loci and genes associated with hair weight and length in Tianzhu White Yak, providing insights into the genetic basis of hair production traits.

## Contribution

The study reports genome-wide significant loci and candidate genes for hair traits in Tianzhu White Yak, enhancing understanding of their genetic mechanisms.

## Key findings

- Chromosome 6 had the highest number of significant SNP loci linked to hair traits.
- Candidate genes like FGF5, CFAP299, and PRDM8 were found to influence hair weight and length traits.
- Functional analysis showed enrichment in cytoplasm and the MAPK signaling pathway.

## Abstract

This study systematically measured gross hair weight and hair length traits across five body regions of 759 Tianzhu White Yak individuals. The BSL trait exhibited moderate heritability, while the BL trait demonstrated high heritability (h2 = 0.450). All other traits showed low heritability. GWASs were conducted using whole-genome resequencing data comprising 22,566,255 high-quality SNP loci. The MLM model identified 519 genome-wide significant loci and 767 chromosome-wide significant loci. Chromosome 6 harbored the highest number of significant SNP loci, while the remaining significant loci were distributed across multiple autosomes. Strong long-range linkage disequilibrium (r2 > 0.7) was observed between numerous significant SNPs on chromosome 6 associated with Gw and HL traits. A total of 73 candidate genes were annotated, including FGF5, CFAP299, and PRDM8. Functional enrichment analysis based on the GO and KEGG databases revealed significant enrichment in cytoplasm and the MAPK signaling pathway. Sanger sequencing results revealed that mutations in the FGF5, CFAP299, PRDM8, ANTXR2, and GPHB5 genes significantly affected the Gw, HL, and BSL traits of Tianzhu White Yak (p < 0.01). Linkage disequilibrium analysis indicated strong linkage disequilibrium (r2 > 0.6) among Sanger-sequenced SNP loci on the same chromosome. From a biological perspective, multiple candidate genes such as FGF5 and CFAP299 are involved in hair follicle cycle regulation, cell proliferation, and metabolic control, suggesting its potential role in hair follicle development and hair shaft growth. This study identifies candidate loci and genes for gross hair weight and hair length traits in Tianzhu White Yak, contributing to elucidating the genetic mechanisms underlying hair production performance.