Diagnostic value of a microsatellite DNA marker for copper toxicosis in West-European Bedlington terriers and incidence of the disease

Recently, linkage of a DNA microsatellite marker to inherited copper toxicosis has been reported in American Bedlington terrier families. Due to the fact that there is little exchange of breeding stock between the USA and Europe, it remains to be investigated whether in Europe the marker is informative and is linked with the disease. We have therefore examined the diagnostic value of the microsatellite marker in the European Bedlington. In 130 dogs at least one year of age (62 from The Netherlands, 35 from Belgium, and 33 from Germany) histo- or cytochemical staining of copper was done in liver biopsies. Based on liver histo- or cytochemistry, 51 dogs were obligate carriers, and 25 dogs had copper toxicosis. The inferred genotypes of these 76 dogs were compared with the marker genotypes. All dogs with the disease were homozygous for the 167 bp marker allele. All obligate carriers were heterozygotes with the 167 bp and a 163-bp alleles. All phenotypically healthy dogs were either homozygous for the 163 bp allele or heterozygous. Thus, the marker was in complete linkage disequilibrium with the putative copper toxicosis gene with the 167 bp allele in phase with the disease allele. The frequencies of the 167 bp and the 163 bp allele, respectively, were 0.33 and 0.67 in Dutch dogs, 0.31 and 0.69 in German dogs, and 0.57 and 0.43 in Belgian dogs. We have confirmed the utility of this marker for diagnosis of inherited copper toxicosis in European Bedlington terriers.