Abstract: Copy number variation (CNV) is widespread in human and animal genomes and is a significant source of genetic variation.In this study, we investigated genome-wide characteristics of CNVs in 2 Mongolia horses and 1 Thoroughbredby using the comparative genomic hybridization (CGH) array method.In total, 210 CNVs were indentified ranging in size from 6 109 bp to 571.87 kb, with an average size of 37.81 kb and a median size of 14.45 kb.By merging overlapping CNVs, we found a total of seventy CNV regions (CNVRs).The length of the CNVRs ranged from 6 151 bp to 573.59 kb with average and median sizes of 38.93 and 14.45 kb and the summary size of CNVRs was 6.19 Mb.CNV gene annotated and functional analysed indicated that the most gene involved olfactory receptor activity, sensory perception of smell, sensory perception of chemical stimulus, sensory perception, cognition and olfactory transduction.To comfirm these findings, quantitave PCR (qPCR) was performed for 5 CNVRs, and found 83.33% of the qPCR results were consistent with the CGH chip.We performed the genome-wide detection of copy number variations in Mongolia horses, and which indicated that CNV was ubiquitous in the horse genome.This research provided foundation for studying the association between the horse CNV and important biological traits.

Key words: Mongolia horse; copy number variation; comparative genomic hybridization; quantitave PCR