Glycogen Storage Disease VII, PFK Deficiency

General Information: Glycogen Storage Disease VII (GSD VII), or PFK Deficiency, affects dogs by disrupting the normal breakdown of glycogen into glucose due to insufficient activity of the phosphofructokinase enzyme. This disruption leads to the destruction of red blood cells (hemolysis) and, to a lesser extent, damage to skeletal muscle cells. Symptoms typically include severe anemia evidenced by pale gums, lethargy, exercise intolerance, and after physical exertion or stress, episodes of red or brown urine, muscle cramps, and jaundice. While the disease does not generally shorten a dog's life expectancy, it significantly impacts quality of life, leading to recurrent health issues and progressive muscle wasting, eventually incapacitating the affected dog.

How to Read Your Dog's Test Results for this Genetic Variant:

Two Variants Detected: Dog Likely Affected

One Variant Detected: Dog Unlikely Affected

No Variants Detected: No Effect

Gene / Testing Information: The genetic basis of Glycogen Storage Disease VII (GSD VII), or PFK Deficiency, is determined through testing for mutations in the PFKM gene. This condition is inherited in an autosomal recessive pattern, meaning that a dog must inherit two copies of the mutated gene—one from each parent—to manifest symptoms of the disease. Carriers of one copy of the mutation do not show clinical signs but can pass the defective gene to their offspring. To manage this genetic issue, it is crucial to perform genetic testing before breeding; mating two carriers yields a 25% chance that each puppy will be affected and a 50% chance that each puppy will be a carrier. To prevent the propagation of this disorder, breeding of known carriers is strongly discouraged. Breeding strategies should focus on pairing carriers with non-carriers to ensure no affected puppies are born, maintaining the health of the breed line. Normal genetic testing results for PFKM do not rule out other genetic conditions, so comprehensive health screening remains essential.