The first DNA test to be made available was the CO4107 marker test, developed by Vetgen in the USA and adopted by the Animal Health Trust in July 1996 following a trial to assess its suitability for use in the UK. This was an indirect test based on the identification of a small section of DNA which had been found to be associated with the mutation thought to cause copper toxicosis. Unfortunately, it soon became apparent that anomalous results were occurring. This was attributed to “recombination” taking place between the marker and the actual gene during the formation of gametes (sperm and eggs), resulting in the marker normally associated with the mutant gene and that associated with the normal gene being “switched over”.
Research into the genetics of copper toxicosis continued and in 2002 A.J.A.van de Sluis and his co-workers at the University of Utrecht announced that they had identified what was, seemingly, the causative gene - the COMMD1 gene (originally named the MURR1 gene). The team identified the mutation as a large deletion in exon2 of the COMMD1 gene and further established that the marker, previously used as the basis for the initial DNA test, was an integral part of this gene. This discovery virtually eliminated the premise that recombination was the cause of the anomalous results obtained with the CO4107 marker test.
A new DNA test (the COMMD1 test) was developed and was introduced by the AHT in July 2005. However, evidence has accumulated over time that supported the speculation that a second gene may be involved. Research is currently being undertaken to attempt to resolve this issue and although considerable progress has been made there is still much work to be done - for the latest information click Here.
An explanation of how the test results from the CO4107 marker test and the COMMD1 test are interpreted can be found at:
Scroll down to the bottom of the Home page and click on “DNA testing” in the “What We Do” list. Click on “Canine DNA Testing” in the “Related Links” panel and then scroll down the page to make the appropriate links for “Bedlington terrier” - “Copper Toxicosis”.
At the bottom of the home page click on “Learn More Canine ” under ”DNA Disease and Genetic Testing” and then click on “CT” in the “Genetic tests “ list.
Although the COMMD1 test, seemingly, had the potential to identify the CT status of a dog, it became evident that some results were incorrect. Consequently, despite the fact that it cannot identify the “carrier” status, examination of tissues obtained by means of a liver biopsy still remains the method for positively diagnosing the disease, i.e. of identifying affected dogs. Moreover, it remains the only way whereby any new DNA test can be validated.
Update on Copper Toxicosis Research.
The research project to identify the postulated “second CT gene” has now been completed. The results of the research were presented at an International Conference in Naples towards the end of 2014 and were well received by the conference delegates. A “peer reviewed” paper has now been published in the February 2016 issue of the “Journal of Trace Elements in Medicine and Biology”.
Clickthe link to view a copy of the research paper
One could say that this is now the end of Stage 1. The next step will be to obtain funding to develop a new DNA test for this second gene and then to establish a new testing protocol . It is highly probable that the new test will be used “in parallel” with the existing COMMD1 test, i.e. the 2 tests will be carried out separately using the DNA extracted from a single cheek swab submitted by the dog’s owner.
An important sequel to the introduction of the new testing regime will be the need for validation. This is particularly pertinent in view of the fact that analysis of the research data has suggested that in some cases there may be other factors involved in the development of the condition.