I am copying the update from Dr. Paula Henthorn at U of Penn. The search for the "TVD gene" continues, with earlier hopes of Chromosome 9 leading to a specific location now disproven. Dr. Sleeper and Dr. Henthorn need more blood samples from TVD affected AND equivocal dogs.
"Tricuspid valve dysplasia (TVD) is a developmental anomaly of the tricuspid valve of the heart, seen in many dog breeds, that has clear evidence of a genetic predisposition in the Labrador Retriever. While inheritance patterns in this breed are not simple, the disease showed autosomal dominant inheritance with incomplete penetrance, in a previous mapping study in one pedigree of Labradors. In this study, a 4Mb region on dog chromosome 9 was associated with the occurrence of this disorder. The purpose of our study was to expand the study of this region, with the immediate goal of refining our knowledge of the location of the “TVD gene”. We identified additional useful polymorphic markers spanning the previously identified 4 Mb disease-associated interval for analysis on the original pedigree, and on a collection of TVD affected dogs and their relatives, and performed SNP chip hybridization and analysis on 41 dogs. Our studies in this larger population of Labrador Retrievers, not closely related, did not identify the chromosome 9 region as associated with TVD. Consequently, we will need to continue collecting DNA from additional TVD affected dogs and their relatives to perform a large genome wide association study. As before these studies would be aimed at the development of linked marker and mutation-based tests that can be used by breeders to reduce the incidence of this heart defect in the breed. Tricuspid valve dysplasia (TVD) has been documented in numerous dog breeds, including Boxers, German Shepherds, Golden Retrievers, Great Danes, Great Pyrenees, Irish Setters, Mastiffs, Newfoundland, Old English Sheepdogs, Shih Tzu, and Weimaraners, and may have a genetic basis in some of these breeds. We expect to generate knowledge and reagents with which to examine TVD affected dogs of other breeds to determine if their disease is related to that found in Labrador Retrievers
A successful outcome from this research could improve the overall quality of life of dogs of many breeds, and further the knowledge of congenital heart disease in veterinary medicine. It may also inform human pediatric medicine, since Ebstein anomaly in children is the comparable disease in humans."
