A genome wide association study between CNVs and quantitative traits in Brown Swiss cattle

Copy Number Variations (CNVs) are DNA sequences of 50 bp up to several Mb long, which can vary in number of copies in comparison with a reference genome. CNVs can be used in association studies to disclose genetic basis of quantitative traits phenotypic variation. Up to date, no genome-wide association study (GWAS) with CNVs and quantitative traits in such a large Brown Swiss population (i.e. with 1116 samples) has been described. The purpose of this study was to perform a GWAS using CNVs with functional, health and productive traits and to asses the impact on farming and breeding practices. The CNV association studies were performed with the Golden Helix SVS 8.4.4 software using a correlation-trend test model. Genes within significant associated CNVs for each trait were annotated with a GO analysis using the DAVID Bioinformatics Resources 6.7. A total of 56 CNVs were significantly associated with one or more of the eight evaluated traits. The greatest association signals were given by three CNVs on chromosome 12 for the fat yield trait and on BTA23 for udder traits. The associated CNVs overlap with 23 different genes annotated on the Bos trams genome assembly (UMD3.1).