Abstract
Purpose :
Although degeneration of the vitreous affects both man and the domestic dog, very little is known about its molecular etiology. We have performed a careful clinical and genetic study in a dog breed in which vitreous degeneration occurs frequently and affects individuals in early adulthood to identify its genetic cause. Dogs have become a widely used spontaneous large animal model for human eye diseases and results from canine studies can inform the molecular etiology of the corresponding human phenotype and its pathophysiology.
Methods :
A study group of Italian Greyhounds in a large pedigree was established from privately-owned pure-bred dogs and included 48 clinically confirmed cases and 10 healthy control dogs that had been examined by veterinary ophthalmologists. In addition, optical coherence tomography was performed to 6 cases and 2 controls to assess retinal pathologies. A genome-wide association study was performed using Illumina Canine HD BeadChip 173K. Allele frequencies between cases and controls were compared with Plink 1.07, GenAbel and BigRR to map the disease associated chromosomal region.
Results :
Veterinary eye examinations revealed early-onset vitreous degeneration in Italian Greyhounds at approximately three years of age. Optical coherence tomography excluded retinal pathologies. Genome-wide association analysis identified a disease associated chromosomal region on the canine chromosome 17 (p=1.66x10-09).
Conclusions :
Here we describe the clinical findings in a canine model of early-onset vitreous degeneration and map its susceptibility locus, harboring candidate genes. Unlike in majority of human patients with vitreous degeneration, the affected dogs did not present with any retinal symptoms. The associated chromosomal region indicates a recessive disease and ongoing whole-genome sequencing experiments are expected to result to the identification of the causative variant. Our results shed new light on the clinical and genetic characteristics of this poorly understood disease and establishes the affected dogs as spontaneous large animal model to further investigate the vitreous biology in healthy and diseased eye.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.