A1. Make sure that your horse is dry. Wrap 30-50 strands of hair from the mane or tail around a comb, a pen, or your finger and pull sharply. You should be able to see the hair bulbs (roots) at the base of the hair. Hair that is cut or broken, and that does not contain the hair bulb, will not provide a DNA sample.
A2. Here is the order form for the Myopathy Panel in the United States for horse owners in the United States. Here is the order form for the Myopathy Panel outside the United States for horse owners outside the United States.
A3. The USDA has a set of requirements to insure that diseases affecting horses are not imported from outside the United States. It is difficult for a small operation like EquiSeq to comply with these requirements. We have developed an alternative to hair samples: dried blood on a card. Horse owners outside the United States need to use this method.
A4. When your sample is received at EquiSeq, we will create a horse profile page. When results are available, they will be posted to that page, and you will receive an email with a link to the results.
A5. A horse's genetic material does not change over its lifetime. A newborn foal can be tested. For young horses, it is best to take hair samples from the tail rather than the mane.
A6. Myofibrillar Myopathy (MFM) is a subtype of PSSM2 that has a specific kind of defect in muscle revealed by a recently developed staining technique. Prior to the development of this stain, these horses were classified as having PSSM2.
A7. PSSM2/MFM are umbrella terms that describe a set of symptoms. Variant forms of different genes cause symptoms that are similar.
A8. Until now, PSSM2 has been defined as having symptoms of exercise intolerance, testing negative for a genetic variant of glycogen synthase associated with PSSM1 (GYS1-R309H or P1), and having abnormal findings on muscle biopsy. If your horse tests positive for the genetic variants associated with PSSM2/MFM, researchers at EquiSeq don't think that a muscle biopsy is necessary.
A9. PSSM2/MFM is an inherited (genetic) condition. It can be passed down to offspring, but it is not contagious.
A10. PSSM1 and PSSM2/MFM are the names of diseases. A horse can have multiple variants (for example, n/P1 n/P2 n/P3 n/P4), but by definition, if this horse has symptoms of exercise intolerance and tests positive for GYS1-R309H (n/P1 or P1/P1), it has PSSM1.
A11. Genetic tests score the presence or absence of a genetic variant. Apart from rare cases of human error, the tests are completely accurate. Because some genetic variants are not fully penetrant, some horses that are n/P2, n/P3, n/P4, n/P8, or n/K1 will not develop exercise intolerance. This means that the tests are not completely predictive. P2/P2, P3/P3, P4/P4, P8/P8, and K1/K1 horses are much more likely to be affected.
A12. The P2, P3, P4, P8, and K1 variants have been seen in many breeds. Some breeds have a high incidence of a particular genetic variant. In some breeds, a particular genetic variant is very rare or absent.
A13. Researchers at EquiSeq regard PSSM2 as untreatable. Symptoms can be managed though a diet and exercise program. Consult your veterinarian for recommendations.
A14. Researchers at EquiSeq regard PSSM2/MFM as untreatable. Symptoms can be managed though a diet and exercise program. Consult your veterinarian for recommendations.
A15. Researchers at EquiSeq regard PSSM2/MFM as untreatable. Symptoms can be managed though a diet and exercise program. Consult your veterinarian for recommendations.
A16. Horses with the P8 genetic variant (n/P8 or P8/P8) require higher levels of vitamin E supplementation to achieve normal levels of vitamin E. Have your horse's serum vitamin E level checked and increase the level of vitamin E supplementation until normal levels are reached. Consult your veterinarian for recommendations.
A17. Researchers at EquiSeq regard PSSM2/MFM as untreatable. Symptoms can be managed though a diet and exercise program. Consult your veterinarian for recommendations.
A18. There are other genetic causes of PSSM2/MFM besides the P2, P3, P4, P8, and K1 variants. Researchers at EquiSeq are working to identify these variants. There are also other conditions that produce symptoms similar to PSSM2/MFM (for example, Lyme disease or EPM). Consult with your veterinarian to obtain the best possible diagnosis for your horse.