Combined homozygosity mapping and candidate gene approach for the identification of disease genes in cattle and sheep

A combined homozygosity mapping/candidate gene approach is recommended for the identification of disease genes for inherited defects in species where the family size is small. We applied this approach in our studies of Neuron al Ceroid-Lipofuscinosis (NCL) in Merino sheep, Chondrodysplasia in Dexter cattle, and Hereditary Zinc Deficiency (A46) in Angus and Holstein-Friesian cattle. We have mapped NCL to sheep chromosome 7, we are investigating a c hromosomal area revealing homozygosity in chondrodysplastic calves, and we have almost completed a whole-genome screen for A46.