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Summary: Background: Belgian horses are commonly affected with ocular squamous cell carcinoma (SCC), the most common cancer of the equine eye. A missense mutation in damage‐specific DNA binding protein 2 (DDB2 c.1013C>T, p.Thr338Met) has been established as a recessive genetic risk factor for ocular SCC in the Haflinger breed. A sample of Belgian horses with unknown SCC phenotype was shown to possess this variant at a similar frequency to the Haflinger breed. Retrospective studies indicate that chestnut coat colour may predispose to the development of SCC. Objectives: To determine if DDB2 c.1013C>T is a risk factor for ocular SCC in a strictly phenotyped sample of Belgian horses. To investigate associations between coat colour loci genotypes and ocular SCC. Study design: Retrospective and prospective case identification, genetic investigation. Methods: Genomic DNA was isolated from blood, hair or formalin‐fixed paraffin‐embedded tissue from 25 Belgian horses with histologically confirmed ocular SCC and 18 unaffected Belgian horses. Association testing of 34 single nucleotide variants from 11 genomic loci and genotyping for DDB2 c.1013C>T and coat colour alleles were performed. Exons of DDB2 were sequenced in four cases and two controls. Associations were analysed by Chi‐square or Fisher's exact tests and relative risk was calculated. Results: Homozygosity for DDB2 c.1013C>T was significantly associated with ocular SCC (P = 7.4 × 10−7). Seventy‐six per cent of affected horses were homozygous for the variant. Relative risk for homozygous horses developing SCC was 4.0 (P = 1.0 × 10−4). Sequencing DDB2 did not identify a variant more concordant with disease phenotype. An association between disease and coat colour loci was not identified. Main limitations: Phenotyping was determined at a single timepoint. Each included horse genotyped as chestnut, so association with this MC1R variant could not be investigated. Conclusions: A missense variant, DDB2 c.1013C>T, p.Thr338Met, is a risk factor for ocular SCC in Belgian horses. A genetic risk test is commercially available. [ABSTRACT FROM AUTHOR]

Research has been conducted on dog breed populations. The authors describe the study of these population carried out via assessing genotypic variation in dog breeds by means of autosomal microsatellite markers distributed across canine genome.

Research has been conducted on idiopatic epilepsy in dogs which is characterized by recurrent seizure activity. The authors describe their efforts to establish molecular linkage between the epileptic phenotype and the locus large effect, which have been achieved via genomic DNA screening from affected Belgian turvuren and sheepdogs possessing polymorphic canine microsatellite markers.

Background: Addison's disease, also known as hypoadrenocorticism, has been reported in many individual dogs, although some breeds exhibit a greater incidence than the population as a whole. Addison's is presumed to be an autoimmune mediated hereditary defect but the mode of inheritance remains unclear. In particular, the heritability and mode of inheritance have not been defined for the Portuguese Water Dog although Addison's is known to be prevalent in the breed. Results: The analyses present clear evidence that establishes Addison's disease as an inherited disorder in the Portuguese Water Dog with an estimate of heritability of 0.49 (± 0.16); there were no differences in risk for disease across sexes (p > 0.49). Further, the complex segregation analysis provides suggestive evidence that Addison's disease in the Portuguese Water Dog is inherited under the control of a single, autosomal recessive locus. Conclusion: The high heritability and mode of inheritance of Addison's disease in the Portuguese Water Dog should enable the detection of segregating markers in a genome-wide scan and the identification of a locus linked to Addison's. Though the confirmation of Addison's disease as an autosomal recessive disorder must wait until the gene is identified, breeders of these dogs may wish to keep the present findings in mind as they plan their breeding programs to select against producing affected dogs. [ABSTRACT FROM AUTHOR]