Q. How long will it take for me to get my test results?
A. Horse owners who pre-order the P2 test will receive their results by October 1, 2016.
Q. How do I pull hair?
A. 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.
Q. How old does my horse need to be for genetic testing?
A. 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.
Q. I read that they aren't sure that Polysaccharide Storage Myopathy type 2 (PSSM2) is inherited. Why do you say that it is?
A. Researchers at EquiSeq have identified a genetic variant that is associated with PSSM2. The genetic variant alters a gene of known function that is required in skeletal muscle.
Q. I heard that PSSM2 can only be diagnosed by muscle biopsy. Do I still need a muscle biopsy for diagnosis?
A. 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 P2 variant, researchers at EquiSeq don't think that a muscle biopsy is necessary to confirm the diagnosis.
Q. Why do some horses with public profiles have test results for P2?
A. EquiSeq has tested a large number of horses for the P2 variant using an experimental test that uses DNA from a blood sample. The commercial test available for pre-order will use DNA from hair samples, like other commercial genetic tests for horses.
Q. Can my horse get PSSM2 from another horse?
A. PSSM2 is an inherited (genetic) condition. It can be passed down to offspring, but it is not contagious.
Q. Can a horse have both PSSM1 and PSSM2?
A. PSSM1 and PSSM2 are the names of diseases. A horse can have both variants (for example, n/P1 n/P2), 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.
Q. How accurate is your test for PSSM2?
A. Genetic tests score the presence or absence of a genetic variant. Apart from rare cases of human error, the tests are completely accurate. Because the P2 variant is not fully penetrant, some horses that are n/P2 will not develop exercise intolerance. This means that the test is not completely predictive. P2/P2 horses are much more likely to be affected.
Q. What breeds have the Quarter Horse PSSM2 (P2) variant?
A. So far, the P2 variant has been seen in Quarter Horses, Paints, Appaloosas, Ponies of the Americas, Tennessee Walkers, Morgans, Arabians, and Paso Finos. It is likely to be present in other breeds as well.
Q. My horse tests positive for the Quarter Horse PSSM2 variant (n/P2 or P2/P2). What should I do?
A. Researchers at EquiSeq regard PSSM2 as untreatable. Symptoms can be managed though a diet and exercise program. Consult your veterinarian for recommendations.
Q. My horse has symptoms of exercise intolerance but tests negative for the Quarter Horse PSSM2 variant (n/n). What does this mean?
A. There are other genetic causes of PSSM2 besides the P2 variant. Researchers at EquiSeq are working to identify these variants. There are also other conditions that produce symptoms similar to PSSM2 (for example, Lyme disease or EPM). Consult with your veterinarian to obtain the best possible diagnosis for your horse.
Q. I don't understand some of the information on this site. Is there a Genetics For Dummies page?
A. Please see our DNA Learning Center and the Glossary. You may find additional useful information on Wikipedia (try searching Wikipedia with terms that you don't understand).