H & W Committee Statement on Lupoid Dermatosis (LD) Genetic Test

12/28/2019

Exfoliative Cutaneous Lupus Erythematosus (ECLE), also referred as Lupoid Dermatosis (LD), is a hereditary form of Chronic Cutaneous Lupus Erythematosus that predominantly affects German Shorthaired Pointers. The disease starts in early life, and affected dogs present with skin inflammation characterized by alopecia (hair loss), scaling of the face, ears, and back, eventually affecting the whole body. Affected dogs often show signs of lameness, pain, and fever. The disease diagnosis is based on the animal history, clinical signs and skin biopsy. Current treatment options are largely focused on managing the symptoms, and affected dogs do not reach complete cure. 

Due to the hereditary aspect of the disease, a DNA based (genetic) LD diagnostic test was developed by researchers at the Section of Medical Genetics at University of Pennsylvania's School of Veterinary Medicine (PennGen). This test has been available to the public since the late 2000’s, and was used to determine affected dogs, carrier dogs or normal dogs based on detection of a genetic mutation that was thought to be causing LD. However, it was brought the GSPCA Health and Welfare committee’s attention that PennGen has recently started to offer two genetic tests for LD. The original test was renamed as “Lupoid Dermatosis (ECLE) Linked Marker” and a new test is available as “Lupoid Dermatosis (Exfoliative Cutaneous Lupus Erythematosus)”. Additionally, PennGen has contacted owners via email, informing them that a “new and more accurate genetic variant” was found and as a result they have retested all samples submitted between March 2013 and November 2019. The GSPCA H&W committee has been made aware of multiple discrepancies in the results between the original LD test and the new test, including multiple dogs that initially received a “carrier” results now being considered “clear”, and clinically symptomatic dogs receiving a “clear” result under the new test. 

The lack of peer-reviewed scientific publications on the development and validation of both LD tests together with the lack of access to any information explaining all the recent changes in PennGen’s testing approach are concerning. Therefore, the GSPCA H&W committee has contacted PennGen requesting that they inform us of the following: 

  1. What are the overall differences between both tests.
  2. What are the genetic markers being tested for each one of the tests, including name of the gene being tested, which specific mutation and any additional pertinent information.
  3. The clinical implication for a dog that is considered “carrier” or “affected” for each one of the tests.
  4. Reference to any peer-reviewed scientific publications on the development and validation of both tests.
  5. Any additional information on the performance of both tests in the general population in terms of % of false positives (normal dogs that tested as carriers or affected) and % of false negatives (affected dogs that tested as normal or carriers) based on the number of dogs PennGen has tested so far.  

As of today, 12/28/19, we have not received a response from PennGen. The GSPCA H&W committee recognizes the impact of these conflicting results in breeders, owners and dogs’ lives. We are committed to obtaining the information necessary to help guide our members towards making the best decisions for their dogs, their breeding programs and for the future of our breed. We will make any update on this matter available to our members and will make future recommendations based on all the information received.

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