BEVA issues warning about unvalidated genetic tests
"We encourage owners to speak with their vets about the evidence basis for decision making when investigating myopathies in horses." - Professor Piercy
Horse owners are being strongly advised against the use of independent and unvalidated genetic tests for certain myopathies. The warning comes from the British Equine Veterinary Association (BEVA), that says the practice has become widespread within some breed groups, despite the lack of evidence to support the tests.
The genetic tests, check for myopathies including diseases known as type 2 polysaccharide storage myopathy (PSSM2), myofibrillar myopathy (MFM) or muscle integrity myopathy (MIM).
Professor Richard Piercy from the Royal Veterinary College said: “Scientists still do not know whether these are diseases at all, or whether they reflect histopathological features of non-specific muscle damage that might have various genetic but also environmental causes.
“It can of course be very tempting for a horse owner, when their horse has signs that might suggest a muscle problem, to seek any answer they can find, particularly when the problem is proving challenging to diagnose and manage.
“It might be even more tempting for an owner to believe an unsubstantiated genetic result when it ‘fits’ with what they have suspected. But given the high prevalence of the genetic variants in the horse population that are tested for, many horses will test positive just by chance – whether or not they have any disease at all.”
Type one PSSM can be diagnosed by DNA testing of a mutation that has been robustly evaluated, but the current advice is to use clinical examination, biochemical testing and muscle biopsy, to identify myopathies in horses.
BEVA does not recommend scientifically unvalidated genetic tests that are offered by companies in Europe and the USA, for diagnosis of equine muscle diseases including PSSM2, MFM and MIM.
Professor Piercy continued: “We encourage owners to speak with their vets about the evidence basis for decision making when investigating myopathies in horses.
“Until results of genetic testing for PSSM2, MFM, MIM and other myopathies in horses are presented in peer reviewed, validated scientific literature that is accepted by the scientific community (as has been the case for PSSM1), we do not recommend their use and certainly do not support veterinary or life decisions being made based on their results.”
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