A knockout mutation associated with juvenile paroxysmal dyskinesia in Markiesje dogs indicates SOD1 pleiotropy.

A juvenile form of paroxysmal dyskinesia segregated in the Markiesje dog breed. Affected pups exhibited clinical signs of a severe tetraparesis, dystonia, cramping and falling over when trying to walk. In most cases, the presentation deteriorated within weeks and elective euthanasia was performed. Pedigree analysis indicated autosomal recessive inheritance. Genome-wide association and homozygosity mapping of 5 affected dogs from 3 litters identified the associated locus on chromosome 31 in the region of SOD1. The DNA sequence analysis of SOD1 showed that the patients were homozygous for a frameshift mutation in the fourth codon. None of the other analyzed dogs of the breed was homozygous for the mutation, indicating full penetrance of the genetic defect. Mutations in SOD1 are known to cause recessive degenerative myelopathy in middle-aged dogs with low penetrance and dominant amyotrophic lateral sclerosis in humans with variable age of onset. Our findings are similar to recent observations in human patients that a loss of function mutation in SOD1 leads to a juvenile neurologic disease distinct from amyotrophic lateral sclerosis.

Heterozygosity testing and multiplex DNA panel screening as a potential tool to monitor health and inbreeding in a small, closed dog population.

BACKGROUND: Selective breeding in populations with a limited effective population size may result in a loss of genetic diversity, which can cause an increased concentration of specific disease liability genes. The Dutch Shepherd Dog (DSD) in the Netherlands is an example of such a breed with a small effective population. OBJECTIVE: To evaluate the measurement of genetic diversity and multiplex DNA panel screening for implementation in a breeding strategy for the Dutch Shepherd Dog (DSD) and to investigate the clinical relevance of potentially identified mutations in the multiplex DNA panel screening. RESULTS: Genome-wide SNP testing showed genetic isolation and reduced genetic diversity within coat variety subgroups of the DSD. Panel screening identified a Von Willebrand's Disease type I mutation. Although decreased Von Willebrand's Factor proteins were significantly lower in DSDs carrying the VWD-I allele compared to the wildtype, clinical follow-up did not show a significant association between the clinical phenotype and VWD-I genotype. CONCLUSIONS: Genetic relationship measurement within a breed population may be a useful tool to enable breeding strategies to conserve genetic diversity. Results from a disease panel screening need to be evaluated for clinical relevance before breed selection restrictions can be considered.

A novel VWF variant associated with type 2 von Willebrand disease in German Wirehaired Pointers and German Shorthaired Pointers.

Von Willebrand disease (VWD), caused by deficiency of the von Willebrand factor (VWF), is the most common bleeding disorder in humans and dogs. The complete cDNA encoding VWF of a German Wirehaired Pointer with type 2 VWD was sequenced, and we found four variants that alter the amino acid sequence. These variants were: c.1657T>G corresponding to p.Trp553Gly; c.1777G>A (p.Glu593Lys); c.4937A>G (p.Asn1646Ser) and c.5544G>A (p.Met1848Ile). A haplotype of the c.1657G, c.1777A and c.4937G alleles co-segregated with the VWF antigen level in a four-generation pedigree with the disease. Healthy dogs of the breed were found that were homozygous for the c.1777A or the c.5544A allele, indicating that these variants do not cause VWD. Dogs that were homozygous for the c.4937G allele and had no signs of a bleeding disorder were observed in the Chinese Crested dog breed. Thus, only the c.1657G variant was found in the homozygous state exclusively in VWD affecteds, and this variant is the strongest candidate to be the cause of VWD type 2 in the German Wirehaired Pointer breed. A screen of German Shorthaired Pointers indicated that the variant also segregates with VWD in this breed.

Paroxysmal Dyskinesia in Border Terriers: Clinical, Epidemiological, and Genetic Investigations.

BACKGROUND: In the last decade, a disorder characterized by episodes of involuntary movements and dystonia has been recognized in Border Terriers. OBJECTIVES: To define clinical features of paroxysmal dyskinesia (PD) in a large number of Border Terriers and to study the genetics of the disease. ANIMALS: 110 affected and 128 unaffected client-owned Border Terriers. METHODS: A questionnaire regarding clinical characteristics of PD was designed at Utrecht University and the University of Helsinki. Thirty-five affected Border Terriers underwent physical examination and blood testing (hematology and clinical biochemistry). Diagnostic imaging of the brain was performed in 17 affected dogs and electroencephalograms (EEG) between episodes were obtained in 10 affected dogs. A genomewide association study (GWAS) was performed with DNA of 110 affected and 128 unaffected dogs. RESULTS: One hundred forty-seven questionnaires were included in the study. The most characteristic signs during episodes were dystonia, muscle fasciculations, and falling over. The majority of owners believed that their dogs remained conscious during the episodes. A beneficial effect of anti-epileptic therapy was observed in 29 of 43 dogs. Fifteen owners changed their dogs' diet to a hypoallergenic, gluten-free diet, and all reported reasonable to good improvement of signs. Clinical examinations and diagnostic test results were unremarkable. The GWAS did not identify significantly associated chromosome regions. CONCLUSIONS AND CLINICAL IMPORTANCE: The survey results and EEG studies provided further evidence that the observed syndrome is a PD rather than epilepsy. Failure to achieve conclusive results by GWAS indicates that inheritance of PD in Border Terriers probably is complex.

Microsatellite diversity of the Nordic type of goats in relation to breed conservation: how relevant is pure ancestry?

In the last decades, several endangered breeds of livestock species have been re-established effectively. However, the successful revival of the Dutch and Danish Landrace goats involved crossing with exotic breeds and the ancestry of the current populations is therefore not clear. We have generated genotypes for 27 FAO-recommended microsatellites of these landraces and three phenotypically similar Nordic-type landraces and compared these breeds with central European, Mediterranean and south-west Asian goats. We found decreasing levels of genetic diversity with increasing distance from the south-west Asian domestication site with a south-east-to-north-west cline that is clearly steeper than the Mediterranean east-to-west cline. In terms of genetic diversity, the Dutch Landrace comes next to the isolated Icelandic breed, which has an extremely low diversity. The Norwegian coastal goat and the Finnish and Icelandic landraces are clearly related. It appears that by a combination of mixed origin and a population bottleneck, the Dutch and Danish Land-races are separated from the other breeds. However, the current Dutch and Danish populations with the multicoloured and long-horned appearance effectively substitute for the original breed, illustrating that for conservation of cultural heritage, the phenotype of a breed is more relevant than pure ancestry and the genetic diversity of the original breed. More in general, we propose that for conservation, the retention of genetic diversity of an original breed and of the visual phenotype by which the breed is recognized and defined needs to be considered separately.

Evaluation of the serotonergic genes htr1A, htr1B, htr2A, and slc6A4 in aggressive behavior of golden retriever dogs.

Aggressive behavior displays a high heritability in our study group of Golden Retriever dogs. Alterations in brain serotonin metabolism have been described in aggressive dogs before. Here, we evaluate whether four genes of the canine serotonergic system, coding for the serotonin receptors 1A, 1B, and 2A, and the serotonin transporter, could play a major role in aggression in Golden Retrievers. We performed mutation screens, linkage analysis, an association study, and a quantitative genetic analysis. There was no systematic difference between the coding DNA sequence of the candidate genes in aggressive and non-aggressive Golden Retrievers. An affecteds-only parametric linkage analysis revealed no strong major locus effect on human-directed aggression related to the candidate genes. An analysis of 41 single nucleotide polymorphisms (SNPs) in the 1 Mb regions flanking the genes in 49 unrelated human-directed aggressive and 49 unrelated non-aggressive dogs did not show association of SNP alleles, genotypes, or haplotypes with aggression at the candidate loci. We completed our analyses with a study of the effect of variation in the candidate genes on a collection of aggression-related phenotypic measures. The effects of the candidate gene haplotypes were estimated using the Restricted Maximum Likelihood method, with the haplotypes included as fixed effects in a linear animal model. We observed no effect of the candidate gene haplotypes on a range of aggression-related phenotypes, thus extending our conclusions to several types of aggressive behavior. We conclude that it is unlikely that these genes play a major role in the variation in aggression in the Golden Retrievers that we studied. Smaller phenotypic effects of these loci could not be ruled out with our sample size.