October 10, 2016

Genetic Screening Reveals Additional Dog Breeds at Risk for Hereditary Disorders

A recent study conducted by researchers from Genoscoper Laboratories reveals dog breeds at risk for hereditary disorders.
By Laurie Anne Walden, DVM, ELS
 A study recently published in PLOS One sheds new light on hereditary diseases in dogs, revealing that gene variants linked to inherited diseases can be found in more breeds than previously reported. The results could be useful in veterinary diagnostics and dog breeding programs, say the authors.
 
“We noted that surprisingly many canine inherited disorders are actually more widespread than indicated by their original discovery studies, which opens up the door for several future scientific investigations,” said Dr Hannes Lohi, of the University of Helsinki, in a press release.
 
Researchers from Genoscoper Laboratories (Helsinki, Finland), the University of Helsinki, and the University of Pennsylvania tested DNA samples from 6788 dogs representing 233 breeds. The samples were originally submitted to Genoscoper for commercial DNA testing. Investigators used a multiplex genotyping microarray to screen for 93 gene variants linked to hereditary disorders in dogs.
 
Of the dogs tested, 17.8% carried at least one disease variant. This percentage is higher than would be expected in the general population, say the authors, because some samples were from relatives of known carriers or from breeding programs that were screening dogs for known heritable diseases.
 
Fifteen disease variants were found in breeds in which they had not previously been reported. The researchers performed further tests in some of the dogs with the mutations. In some cases, they found clinical signs of the inherited disease in additional breeds.
  • Factor VII deficiency causes coagulopathy in beagles, Scottish deerhounds, and Alaskan Klee Kais. Researchers found the mutation associated with Factor VII deficiency in 10 additional breeds. Further investigation revealed coagulation deficits in some of the Welsh springer spaniels carrying the mutation.
  • The gene variant linked to urate urolithiasis in Dalmatians was found in six additional breeds. The investigators found elevated uric acid concentrations in urine samples from dogs carrying the variant.
  • Researchers identified the gene variant linked to primary lens luxation (prevalent in terrier breeds) in Danish-Swedish farmdogs. Ophthalmic examination revealed clinical lens luxation in four of five Danish-Swedish farmdogs that were homozygous for the mutation.
  • Other clinically relevant findings were associated with progressive early-onset cerebellar ataxia, dwarfism (chondrodysplasia) in Chinooks, familial nephropathy in Welsh springer spaniels, and canine multifocal retinopathy.
 
Interpretation of DNA screening should take into account the clinical relevance (or lack thereof) of the results, say the authors. “…There is a need for careful follow up of any unexpected discoveries,” they write. “Panel screening, as any single DNA test, should only be viewed as one part of a breeding decision and strategy.”
 
The study was funded by various foundations, the Academy of Finland, and the National Institutes of Health. One author co-founded Genoscoper, which provides commercial DNA testing for dogs. Three authors are employed by Genoscoper. One author is employed by the PennGen laboratory (University of Pennsylvania), a nonprofit entity that provides genetic testing for animals.
 
Dr. Laurie Anne Walden received her doctorate in veterinary medicine from North Carolina State University. After an internship in small animal medicine and surgery at Auburn University, she returned to North Carolina, where she has been in small animal primary care practice for over 20 years. Dr. Walden is a board-certified editor in the life sciences and owner of Walden Medical Writing, LLC.
 

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