Summary about Disease
Phosphofructokinase (PFK) deficiency, also known as Tarui disease (Glycogen Storage Disease Type VII), is a rare genetic metabolic disorder affecting the enzyme phosphofructokinase, which is crucial for glycolysis (the breakdown of glucose for energy). This deficiency primarily impacts muscle cells and red blood cells, leading to muscle cramps and hemolytic anemia.
Symptoms
Muscle cramps and pain, especially during exercise
Exercise intolerance
Fatigue
Myoglobinuria (presence of myoglobin in the urine, causing it to be dark or reddish)
Hemolytic anemia (premature destruction of red blood cells)
Elevated levels of creatine kinase (CK) in the blood
Nausea and vomiting after exercise
In some cases, jaundice (yellowing of the skin and eyes) due to the breakdown of red blood cells.
Causes
PFK deficiency is caused by mutations in the PFKM gene. This gene provides instructions for making the muscle subunit of the phosphofructokinase enzyme. The condition is inherited in an autosomal recessive manner, meaning an individual must inherit two copies of the mutated gene (one from each parent) to develop the disease. Individuals who inherit only one copy are carriers and usually do not show symptoms.
Medicine Used
There is no specific cure for PFK deficiency. Treatment focuses on managing symptoms and preventing complications:
Dietary modifications: A carbohydrate-rich diet may worsen symptoms. Some individuals may benefit from a ketogenic diet or other dietary changes to reduce reliance on glycolysis. Consultation with a registered dietitian is essential.
Supplementation: Ribose supplementation has been tried, but its effectiveness is not definitively established.
Management of hemolytic anemia: In severe cases, blood transfusions may be necessary.
Avoidance of strenuous exercise: Individuals should avoid activities that trigger muscle cramps and fatigue.
Management of secondary complications: If jaundice, kidney problems, or other complications arise, they must be managed accordingly.
Is Communicable
No. PFK deficiency is a genetic disorder and is not contagious or communicable.
Precautions
Genetic counseling is important for families with a history of PFK deficiency.
Avoid strenuous exercise and activities that trigger symptoms.
Maintain a healthy lifestyle.
Consult with a doctor or registered dietitian to manage dietary requirements.
Monitoring of urine for myoglobinuria after exercise.
Individuals who have PFK deficiency should inform their healthcare providers before any medical procedures or surgeries.
How long does an outbreak last?
PFK deficiency is not an "outbreak" but a chronic genetic condition. Symptoms can be triggered by exercise or other stressors, but the underlying condition is lifelong. Individual episodes of muscle cramps or hemolytic events can last for hours to days, depending on the severity and trigger.
How is it diagnosed?
Diagnosis typically involves:
Clinical evaluation: Assessment of symptoms and medical history.
Blood tests: Elevated creatine kinase (CK) levels, evidence of hemolytic anemia (low hemoglobin, elevated bilirubin), and enzyme activity assays to measure PFK activity in red blood cells and/or muscle tissue.
Muscle biopsy: A muscle biopsy may be performed to assess PFK activity in muscle tissue.
Genetic testing: Identification of mutations in the PFKM gene confirms the diagnosis.
Timeline of Symptoms
The onset and severity of symptoms can vary. Some individuals may experience symptoms in early childhood, while others may not develop noticeable symptoms until adulthood. The timeline can vary significantly from person to person.
Early childhood/Adolescence: Exercise intolerance, muscle cramps after physical activity.
Adulthood: Persistent fatigue, muscle weakness, episodes of myoglobinuria after strenuous activity, potentially leading to kidney complications if untreated. Hemolytic anemia can present at any age.
Important Considerations
Genetic counseling: Crucial for families with a history of PFK deficiency to understand the inheritance pattern and risk of passing the condition to future generations.
Personalized management: Management strategies should be tailored to the individual's specific symptoms and needs.
Regular monitoring: Regular monitoring of blood counts, kidney function, and other relevant parameters is important to detect and manage complications.
Awareness of potential triggers: Identify and avoid activities or situations that trigger symptoms.
Support groups: Connecting with other individuals and families affected by PFK deficiency can provide valuable support and information.