BHF Glaucoma Research Proposal
Primary Closed Angle Glaucoma (PCAG) is an inherited eye disease found in multiple dog breeds, including the Bouviers des Flandres. It is characterized by an abnormal elevation in intraocular eye pressure (IOP). This increase in IOP results in extreme pain and damage to the optic nerve, leading to blindness. Treatment of PCAG is expensive, time-consuming, and often not very successful. New DNA methodologies have provided us with powerful tools that can identify affected and carrier animals and can help eliminate these animals from our breeding populations.
As a part of the Bouvier Health Foundation’s Glaucoma awareness campaign, we have reached out to the country’s top researchers in the field of canine genetics and glaucoma to propose a genetic study on Glaucoma in Bouviers. This study will look for genetic markers for glaucoma. The study will perform Whole Genome Sequence (WGS) analysis on 2 groups of dogs: affected dogs (dogs who have been diagnosed with PCAG and unaffected dogs (dogs who have exhibited no signs of glaucoma by 10 years of age). The WGS data from the affected and unaffected dogs will be compared to identify DNA sequence variants.
The BHF Board has unanimously voted to fund this project. We are currently looking for dogs to participate in this study who have been diagnosed with Primary Angle Closure glaucoma.
We are in the process of fundraising and welcome any contributions.
Proposal to Identify the Molecular Genetic Basis of Glaucoma in Bouvier Dogs
University of Missouri Canine Genetics Laboratory
Based on the information we have been provided, we hypothesize that glaucoma in Bouvier dogs is an autosomal recessive disease that is the result of a single mutation. We propose to use whole genome sequencing and candidate mutation genotyping to identify this mutation.
For this study we will perform whole genome sequence (WGS) analysis on at least 4 dogs from the same litter, 2 of which have been definitively diagnosed with glaucoma and 2 of which have not exhibited signs of glaucoma by 10 years of age. Dogs from additional litters that include both affected and unaffected dogs will be included in the study as available.
The WGS data from the affected and unaffected dogs will be compared to identify those DNA sequence variants that are uniquely homozygous in the affected dogs (and not homozygous in the unaffected dogs or in a pool of over 350 dogs of other breeds that did not have glaucoma from which we already have DNA samples). We anticipate that this will narrow down the number of variants that might be responsible for the disease to just one or two. The more dogs we have for the analyses, the more we can narrow down the candidates based on WGS data.
Once we have identified candidate mutations with the WGS analysis, we will develop a genotyping assay for each candidate mutation and screen up to 50 Bouviers for which we have definitive information on whether they have glaucoma or not. To confirm that we have identified the causal mutation, we will look for concordance between the genotype and the disease status. For this part of the study, we may be able to use primarily DNA that has already been banked if we can get glaucoma status information from the owners.
We will identify DNA samples in our archive from Bouviers that are currently at least 10 years of age (or were before they died).
We will send surveys to the owners of these dogs to determine whether they suffered from glaucoma.
We will genotype all of the dogs for which we are able to obtain reliable glaucoma status, including at least 20 affected dogs.
Once we have established that there is concordance between the disease and the genotype, we will be able to offer a screening test for the causal mutation. We have used a similar approach to find the causal mutations and develop screening tests for over 70 hereditary diseases in dogs.
We will proceed as follows:
1) Identify litters of dogs that are at least 10 years of age and include at least 2 that have been definitively diagnosed with glaucoma and 2 that have not exhibited any signs of glaucoma.
2) Collect DNA samples and health information on all littermates from (1) and from the parents of the litter if available (may be in our DNA archive).
3) Collect glaucoma status and pedigree information on at least other 50 Bouviers from which we have or will obtain DNA that are at least 10 years of age.
4) Perform WGS analysis on the dogs from (1) and identify sequence variants that are uniquely homozygous in the affected dogs relative to their unaffected littermates and 350 dogs of other breeds that did not have glaucoma. We anticipate that this analysis will identify one or two likely candidate mutations.
5) Screen at least 50 Bouviers of known glaucoma status from (3) for the candidate mutations. If a candidate mutation is concordant with glaucoma status, offer a screening test that can distinguish between dogs likely to develop glaucoma, carriers that can pass on the mutation but that will not develop glaucoma, and dogs in which both copies of the gene are normal.
Note that the identities of the dogs and their owners who participate in this study will be kept confidential and that any results relating to specific dogs will be reported only to the person who submitted the blood sample and health information. Dogs will be de-identified in any public reports of our findings.
Thank you for your interest and support!