GWAS and selection signature analyses of whole-genome sequencing data identify genes associated with body size in Duolang sheep.

INTRODUCTION: Duolang sheep is a meat-fat dual-purpose breed originating from Xinjiang, China, and the genetic basis of body size variation in this breed remains unclear. METHODS: Whole-genome resequencing was performed on 224 Duolang sheep with complete records for six body size traits. After variant calling, imputation, and quality control, 19.65 million high-quality SNPs were retained. After linkage disequilibrium pruning, 2.1 million relatively independent SNPs were used for a mixed linear model GWAS in GEMMA. Tajima's D and integrated haplotype score analyses were performed in a kinship-filtered subset of 60 animals, and SheepGTEx data were used to characterize tissue expression patterns. RESULTS: The GWAS identified 24 significant SNPs for height, body length, chest girth, shoulder width, and hip width. Integration of GWAS intervals with selection-signal regions prioritized 31 candidate genes, including CA10, WDR45B, FADS2, LGALS12, and CTNNA2. Multi-tissue expression profiles provided functional context for the prioritized genes. DISCUSSION: These findings provide insight into the genetic architecture of body size traits in Duolang sheep and identify candidate loci for future validation and genetic improvement studies.