In recent years multiple dogs of the Old English Sheepdog (OES) breed have been diagnosed with an ocular (eye) disease that can affect multiple parts of the eye and is therefore known as multiocular defect (MOD). Most affected dogs suffer from cataracts, but additional abnormalities can include any of the following:
- microphakia (small lens),
- lens coloboma (a hole in the lens),
- macrophthalmos (enlarged globe),
- retinal detachment,
- vitreopathy and
- retinal degeneration
Research
The Kennel Club Genetics Centre (KCGC) at the University of Cambridge has been investigating the genetics of MOD in the Old English Sheepdog breed. By analysing the whole genome sequence of an affected OES generated via the Give a Dog a Genome Project, the team were able to identify the likely causal variant for MOD. The variant is a single nucleotide substitution located within an exon (the part of the gene that creates the protein) of a gene called COL11A1. The variant is predicted to change the amino acid sequence of the corresponding protein in a way that damages the protein and is therefore a ‘missense’ variant. It has a dominant mode of inheritance as dogs with either one or two copies of the variant are clinically affected by MOD.
Mutations in COL11A1 have been reported to cause a dominant form of Stickler Syndrome (STL2) in humans, which shares clinical features observed in MOD affected OES. There is evidence that affected dogs with 2 copies of the variant, i.e. homozygous for the variant have a more severe phenotype. The disease has an early age of onset.
For enquiries about the research, contact the Kennel Club Genetics Centre.
DNA Test
The results of this study are currently being prepared for submission to a scientific, peer-reviewed journal. In the meantime, a DNA test for MOD In OES Is exclusively available from Canine Genetic Testing, and can either be bought as a single test or as part of a bundle of discounted tests (available from 9 January 2023).
