Copy number variations at LEPR gene locus associated with gene expression and phenotypic traits in Chinese cattle.

Current evidences show that copy number variations (CNVs) are linked to complex phenotypic traits. Leptin receptor (LEPR) gene plays a critical role in energy homeostasis and fat development and re-sequencing of the cattle genome revealed the CNV region (herein referred to as "I3 DNA") within the LEPR intron 3. In the present study, we qualified copy numbers of I3 DNA within LEPR gene in four cattle breeds (Qinchuan, Nanyang, Jinnan and Xianan) by quantitative PCR, and explored their impacts on LEPR gene expression and phenotypic traits in Qinchuan and Nanyang cattle. The results showed that more individuals in Nanyang are with loss of the I3 DNA copy number than that in the others. Additionally, I3 DNA CNVs exhibited a significant negative correlation with LEPR gene expression (P < 0.05). Association analysis showed that gain/normal copy number types performed better traits of body weight, body height and body length than the loss type in Nanyang. To the best of our knowledge, this is the first evidence of the association between LEPR CNVs and cattle traits, and this may help deep understanding of the function of CNVs which may be promising markers for beef cattle breeding and genetics.