Copy number variation of the HPGDS gene in the Ashidan yak and its associations with growth traits.

Copy number variation (CNV) is a structural variation at the submicroscopic level of the genome, which can affect gene-related phenotypes by changing genes dosage and transcript structure. Hematopoietic prostaglandin D synthase (HPGDS) is a member whose functions are closely related to weight gain and inflammatory diseases of the glutathione S-transferase (GSTs) family. In this study, the growth characteristics (body weight, withers height, body length, and chest girth) of 336 Ashidan yaks were monitored at four stages (6 months, 12 months, 18 months, and 30 months). In addition, CNV of the HPGDS gene was detected, discovered relationships of CNV with growth traits, and explored the level of gene expression. Based on the statistical analysis by IBM SPSS software, significant correlations were observed between HPGDS-CNV and body weight in 12-month-old yak (P < 0.01), 18-month-old yak (P < 0.001) and 30-month-old yak (P < 0.001) and body length in 18-month-old yak (P < 0.05) and 30-month-old yak (P < 0.05), respectively. Additionally, the individuals with gain copy number type performed better in body weight and body length than those with normal or loss copy number type. To our best of knowledge, this is the first time to make efforts to probe into the role of HPGDS-CNV and its interaction with livestock growth traits. Our results suggested that the CNV of the HPGDS gene may be an active candidate gene for the marker-assisted selection (MAS) of yaks.