PSVIII-41 Study of functional variants in homozygous islands in Nelore cattle

The aim of this study was to identify functional variants within runs of homozygosity (ROH) islands present in the genome of Nellore cattle. Genotypic information of 3,492 animals and 755,319 single nucleotide polymorphism (SNPs), were used. ROH segments were detected using PLINK software. Only ROH segments shared by more than 50% of the population individuals were used for identifying homozygosity islands. The islands functional variants were classified using the VEP tool (predictor of variant effect) from ENSEMBL software. If the variant SIFT score was less than 0.05 it was considered to be “deleterious,” otherwise it was “tolerant.” We found five islands of homozygosity, located in chromosome 5, 7, 12, 21 and 26. Within the islands, a total of 1,181 variants were processed by VEP and all of them were recognized as existing variants. In total, 51 overlapped genes and 69 overlapped transcripts were found. Most of the variants were SNPs located in the intronic regions (55%), followed by intergenic spaces (14%), upstream (13%) and downstream gene variants (12%). The intronic variants can be related to specific QTLs, either because they are associated with regions affecting gene expression or in linkage disequilibrium with the causative mutation or even because they have an unknown function. Only a small portion of the variants is in synonymous regions (4%), splice regions (1%), untranslated regions (UTRs) (1%) or are missense variants (1%). We have found 11 missense variants, being three considered deleterious and eight tolerant. The deleterious variants were annotated: INHBC, SMIM33 e FBXW4 genes. The knowledge of functional variants distribution is important for improving annotation of the bovine genome. This study was financed in part by the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior - Brasil (CAPES) - Finance Code 001 and by Sao Paulo Research Foundation FAPESP (grants 2018/04313-7 and 2017/10630–2).