A deletion variant within the FGF5 gene in goats is associated with gene expression levels and cashmere growth

The FGF5 gene has been associated with the regulation of fibre length in mammals, including cashmere goats. A deletion variant at ~14 kb downstream of the FGF5 gene showed significant divergence between cashmere and non-cashmere goats in previous studies. In this study, we designed specific primers to genotype the deletion variant. The results of gel electrophoresis and Sanger sequencing revealed that a 507-bp deletion mutation is located at 95 454 685-95 455 191 of chromosome 6 in goats. Genotyping data from a large panel of 288 goats showed that the deletion at the FGF5 gene locus appeared to be associated with cashmere length. The deletion variant was close to fixation (frequency 0.97) in cashmere goats. Furthermore, electrophoretic mobility shift assays for evaluating DNA-protein interaction and mRNA expression levels of FGF5 suggested that the deletion variant may serve as a cis-acting element by specifically binding transcription factors to mediate quantitative changes in FGF5 mRNA expression. Our study illustrates how a structural mutation of the FGF5 gene has contributed to the cashmere growth phenotype in domestic goats. The deletion mutation within the FGF5 gene could potentially serve as a molecular marker of cashmere growth in cashmere goat breeding.