Investigation of a Possible Novel Genetic Mutation in Brangus Calves with Proportionate Dwarfism

Abstract

The University of Nebraska - Lincoln was contacted in May, 2018, with reports of calves born with proportionate dwarfism and in at least one case, mild scoliosis. The calves share the same sire and pedigree relationships observed between the sire and dams of the affected calves suggested a genetic basis of the condition. The purpose of this study was to use genomic tools to attempt to identify genomic variant(s) causative of small size and skeletal deformities in these Brangus calves. After many analyses, no clear candidate variants were identified by any method employed. Variants that fit one of the hypothesized modes of inheritance across all cases in the regions of interest were rare, and when present, had no clear functional impact. If the phenotype observed were due to a simple Mendelian cause, it would be expected that GWAS and homozygosity mapping analyses would each point to a similar region of the genome, and GWAS associations would include multiple, linked markers; this unfortunately was not the case.