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Molecular basis of canine muscle type phosphofructokinase deficiency
B F Smith1, H Stedman, Y Rajpurohit
1Section of Medical Genetics, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6010, USA.
Abstract:
Muscle type phosphofructokinase (M-PFK) deficiency is a rare inherited glycogen storage disease in humans that causes exertional myopathy and hemolysis. The molecular basis of canine M-PFK deficiency, the only naturally occurring animal homologue, was investigated. Lack of M-PFK enzyme activity was caused by a nonsense mutation in the penultimate exon of the M-PFK gene, leading to rapid degradation of a truncated (40 amino acids) and therefore unstable M-PFK protein. A polymerase chain reaction-based test was devised to identify M-PFK-deficient and carrier animals. This represents one of only a few inborn errors of metabolism where the molecular defect has been identified in a large animal model which can now be used to develop and assess novel therapeutic strategies.
Insights
Canine muscle type phosphofructokinase (M-PFK) deficiency, a genetic disorder causing exertional myopathy, results from a mutation causing M-PFK protein degradation. A DNA test can now identify affected dogs and carriers for this rare metabolic disease.
Area of Science:
- Biochemistry
- Genetics
- Veterinary Medicine
Background:
- Muscle type phosphofructokinase (M-PFK) deficiency is a rare inherited glycogen storage disease.
- This condition causes exertional myopathy and hemolysis in humans.
- Canine M-PFK deficiency is the only known natural animal model.
Purpose of the Study:
- To investigate the molecular basis of M-PFK deficiency in dogs.
- To develop a diagnostic test for canine M-PFK deficiency.
Main Methods:
- Investigated the M-PFK gene in affected dogs.
- Identified a nonsense mutation in the penultimate exon.
- Developed a polymerase chain reaction (PCR)-based genetic test.
Main Results:
- A nonsense mutation in the M-PFK gene was identified as the cause.
- The mutation leads to rapid degradation of an unstable, truncated M-PFK protein.
- A reliable PCR-based test was successfully developed to detect deficient and carrier animals.
Conclusions:
- The molecular defect in canine M-PFK deficiency is a nonsense mutation leading to protein instability.
- This canine model is valuable for studying inborn errors of metabolism and developing therapies.
- A genetic test enables identification of affected and carrier dogs, aiding breeding programs and research.