Research Update Summer 2005

This information is from a report by John Dillberger, DVM, to the Scottish Deerhound Club of America. It is reprinted here with his permission.

In the past year the Scottish Deerhound Club of America collaborated with Dr. Paula Henthorn at the University of Pennsylvania to study cystinuria. In 2004 the SDCA Board approved funding of a $5,800 grant to support this research, using money from the Canine Health Foundation (CHF) Donor-Advised “Bunnie Austin” Fund. The second installment of $2,900 was paid in January 2005.

Dr. Henthorn provided a progress report to the CHF in November 2004, which is the most recent update. The summary of recent progress reads:

"This has been one of the most productive periods in our long-term study of cystinuria. We have confirmed a second disease-causing mutation, generated preliminary data that point to a previously undescribed mutation in a third breed [Labrador Retriever], and have substantially increased our understanding of the natural history of the disease. We have collected DNA from several extended families, and have nearly completed the analysis of the SLC7A9 gene as a candidate gene. The pending availability of a database of canine single nucleotide polymorphisms (SNPs), made possible by the canine genome sequencing efforts, will allow us to perform association studies in the regions of candidate genes. Our discovery of both early and late stone-forming dogs within a single breed (Australian Cattle Dogs) is an extremely interesting, and potentially very useful, finding. We are extremely excited about our upcoming year of research on cystinuria."

Some other interesting points:

  • Analysis of DNA from families of Mastiffs, English Bulldogs, and Scottish Deerhounds has begun. Most affected dogs in these breeds are males, suggesting that the gene responsible for cystinuria is on the X chromosome. Seven potential markers on the X chromosome have been analyzed, and none segregates with affected dogs in any breed. Additional markers are being analyzed.
  • Efforts have begun to develop a urine-based screening test for cystinuria, based on feeding dogs excess amount of dibasic amino acids. These would show up in the urine an affected dog but would NOT be able to precipitate and form stones. If this effort succeeds, then breeders would have a more sensitive test to use on young dogs, before they are bred, to determine if they are at risk of forming cystine stones.

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