August 2002

7th World Congress on Genetics Applied to Livestock Production, August 19-23, 2002, Montpellier, France

IDENTIFICATION OF THE GENE CAUSING CHONDRODYSPLASIA IN DEXTER CATTLE. J. A. L. Cavanagh, I. Tammen, P. A. Windsor, F. W. Nicholas and H. W. Raadsma. Reprogen, The University of Sydney, PMB 3 Camden 2570, Australia.

Dexter cattle are a small breed of cattle originating in Ireland in which there have been reports of chondrodysplastic foetuses, an incompletely dominant form of lethal dwarfism. The aim of this study was to find the gene responsible for chondrodysplasia, and develop a DNA-test. A combined homozygosity mapping and candidate gene approach was used. A candidate gene located in a region of interest was screened and a disease causing mutation was identified. The mutation is a 4 bp insertion causing a frame shift, which in turn leads to a premature termination codon. A DNA–test was developed to identify animals heterozygous for the mutation. The DNA-test will be available to the Dexter breeders this year. The test will be an invaluable tool for Dexter breeders, potentially eliminating the occurrence of chondrodysplastic calves.