2014 Research Funded by YTCAF
Each year the AKC Canine Health Foundation send the YTCA Foundation a list of grant requests for funding that they have screened and think would be of interest to breeders and owners of Yorkshire Terriers as well as dog fanciers in general. As an independent entity spun off from the Parent club to preserve our tax exempt status, the YTCAF receives no financial support from the YTCA's participating in efforts such as the Purina Circles program. Instead all of our funding comes from memorials made by individual donors and fund raising efforts such as the online auctions and breeding calendar sales.
The Board members carefully considered the following factors in each request in order to optimize research dollars:
Potential of the research to benefit Yorkshire Terriers in particular and all dogs in general.
Previous research success of the primary investigators
Use of the grant project to help veterinary students, new veterinarians and academicians get started in their chosen field of research (Acorn projects).
The Board voted to support the following CHF grants for 2014.
Frank G. Van Steenbeek, DVM, PhD
Utrecht University, The Netherlands
RATIONALE: Extrahepatic portosystemic shunt (EHPSS) is a congenital liver disorder in which an abnormal vascular connection between the portal vein and the vena cava or vena (hemi)azygos is established during embryonic development. As a consequence portal blood bypasses the liver lobules resulting in severely impaired liver growth and atrophy of hepatocytes, leading to reduced hepatic functions and eventually death. The disorder occur frequently in a large number of small sized dog breeds and has a proven genetic background. Preliminary results in the genetic causes of EHPSS identified two small chromosome regions responsible for the disease. The responsible genes and their pathways are not yet known and these may be important for pathologic vascular derangements in other diseases (microvascular dysplasia, portal hypertension and formation of acquired portosystemic collateral vessels in fibrotic liver diseases).
HYPOTHESIS/OBJECTIVES: The objective of this project is to elucidate the gene mutations that cause EHPSS in several dog breeds. A genetic test will be developed which will be instrumental in the prevention of the disease. In addition, we will investigate the involvement of these causative genes and their role in other diseases characterized by abnormal vascularization.
STUDY DESIGN: The DNA sequence analysis of positional candidate genes identified before will be completed by resequencing DNA regions poorly covered by the previously performed Next Generation Sequencing experiments. The expression of these genes in liver tissue from patients affected by extrahepatic portosystemic shunts and liver tissue of dogs with other pathologic vascular derangements will be measured. The cellular localization of the encoded proteins will be investigated using immunohistochemistry. The role of the defective genes in vasculogenesis will be determine in the in vitro angiogenesis model.
PRELIMINARY DATA: A genome wide association study was performed on 48 Cairn terriers with EHPSS and 48 controls. Initially we observed three regions of interest. The regions were extensively evaluated by Next Generation Sequencing in 47 cases and 49 breed matched controls of 7 breeds. In addition, selections from a panel of 198 cases and 182 controls from 29 breeds were SNP genotyped in the regions. These analyses excluded one region and narrowed down the two remaining regions of interest, but no clearly functional variations were observed in the coding regions of the remaining candidate genes. The same haplotype in eight consecutive SNPs in the first region had an average frequency in affected Cairn terriers, Jack Russell terriers, Maltese, Miniature Schnauzers, Shih Tzu, West Highland White terriers and Yorkshire terriers of 0.5 whereas the frequency in controls was 0.02. In the second region a common haplotype was observed with an average frequency of 0.8 in the cases of these same breeds while the frequency in controls was 0.2. The two regions together comprise eight genes. Two genes were selected, one from each region, based on known endothelial expression patterns in zebrafish. Knockout experiments in zebrafish using morpholinos resulted in disturbed development of the relevant vascular structures during embryogenesis for both genes.
EXPECTED RESULTS: We expect to pinpoint DNA variations responsible for EHPSS in Cairn terriers, Jack Russell terriers, Maltese, Miniature Schnauzers, Shih TZU, West Highland White terriers and Yorkshire Terriers.
POTENTIAL IMPACT FOR ANIMAL HEALTH: With the knowledge of the genetic factors we will develop a DNA test to assist breeders. By using the test it should be possible to eradicate this severe disease in several dog breeds. We also anticipate a role for these genes in the vascular derangements, which are part of the pathogenesis of other chronic progressive liver diseases. If so, this may provide ways to intervene in these presently incurable diseases.
Portosystemic shunts, also known as liver shunts, are an inherited condition in which abnormal blood vessels direct the flow of blood around the liver and directly into the body’s blood circulation, bypassing filtration and processing by liver cells. Shunting of blood around the liver leads to severely impaired liver growth and cell atrophy, as well as reduction in normal liver function. When the liver loses its ability to clear toxins from the blood, toxins accumulate in the body, and the animal can develop hepatic encephalopathy. This metabolic disorder affects the central nervous system, and, if untreated, can be fatal.
Extrahepatic portosystemic shunts that form outside the liver are frequently diagnosed in a number of small-breed dogs. The mode of inheritance appears complex, but preliminary genetic research from investigators at Utrecht University in the Netherlands identified two chromosomal regions, each containing eight candidate genes, that appear to be associated with this disorder. Two of these genes have been shown to be involved in the formation of vascular structures. In continued research funded by Morris Animal Foundation, these researchers are further characterizing these eight genes, looking for differences in DNA, RNA and protein production between healthy dogs and dogs affected by extrahepatic portosystemic shunts. So far, the researchers have investigated the DNA and RNA differences and are in the process of analyzing their data. In the next six months, they will continue their work on protein differences and will evaluate the role of the two strongest candidate genes in abnormal blood-vessel formation.
Successful identification of genetic mutations associated with this liver condition would be a critical first step toward the development of a diagnostic test that would help breeders eradicate this severe and potentially fatal disease in several dog breeds. The findings may also provide insight into how other chronic progressive liver diseases develop.
$3,000 plus match
W. Jean Dodds, DVM with Hemopet and
Ronald Schultz, DVM, University of Wisconsin.
$3,000 WHICH IS BEING MATCHED
Many states have changed their Rabies laws since the Rabies Challenge began. Two anonymous dog lovers have generously agreed to $12,500 matching gift to The Rabies Challenge Fund to help raise the additional funds needed to perform the first of the challenge phases of this research. There are two phases to this research, one is a five year challenge and the second is a seven year challenge. The YTCAF has supported this effort since its inception and therefore, donated to this research grant again this year to take advantage of the matching funds.