glycogen storage disease VII

Glycogen Storage Disease Type VII (GSDVII): A Rare Metabolic Disorder

Glycogen storage disease type VII, also known as GSDVII or Tarui's disease, is a rare inherited metabolic disorder caused by an inability to break down glycogen in muscle cells. This condition leads to the accumulation of glycogen in muscles, resulting in various symptoms and complications.

Key Features:

• Inherited Disorder: GSDVII is an autosomal recessive genetic disorder, meaning that individuals must inherit two copies of the mutated gene (one from each parent) to develop the condition.
• Muscle Cramping and Weakness: The most common symptom of GSDVII is exercise-induced muscle cramps and weakness, which can range from mild to severe.
• Exercise Intolerance: Individuals with GSDVII often experience fatigue and intolerance to physical activity due to their muscles' inability to break down glycogen.
• Myoglobinuria: In some cases, myoglobin (a protein found in muscle cells) may be released into the urine, leading to a condition called myoglobinuria.

Types of GSDVII:

There are four types of GSDVII, which differ in their signs and symptoms. The classic form is the most common type, characterized by exercise-induced muscle cramps and weakness.

Clinical Features:

• Early Onset: Symptoms typically begin in early childhood, but some individuals may experience symptoms as infants or later in adulthood.
• Painful Cramps or Contractures: Muscle cramping and contractures are common features of GSDVII, particularly after exercise.
• Hyperuricemia: Elevated levels of uric acid in the blood (hyperuricemia) can occur due to the breakdown of muscle cells.

References:

• [1] Koralkova P, Grau JM, Manu Pereira Mdel M, Van Wijk R. First description of phosphofructokinase deficiency in spain: identification of a novel homozygous missense mutation in the PFKM gene ...
• [2] Glycogen storage diseases are a group of diseases where the body’s form of stored energy (glycogen) cannot be broken down into smaller pieces of sugars (glucose) for the body to use.
• [6] Glycogen storage disease VII is an autosomal recessive metabolic disorder characterized clinically by exercise intolerance, muscle cramping, exertional myopathy, and compensated hemolysis. Myoglobinuria may also occur.
• [10] Definition. Glycogen storage disease VII is an autosomal recessive metabolic disorder characterized clinically by exercise intolerance, muscle cramping, exertional myopathy, and compensated hemolysis. Myoglobinuria may also occur. The deficiency of the muscle isoform of PFK results in a total and partial loss of muscle and red cell PFK activity ...

Glycogen storage disease type VII (GSDVII) is characterized by a range of signs and symptoms that can vary in severity and age of onset.

Common symptoms:

• Muscle weakness and stiffness [12]
• Painful muscle

Glycogen storage disease type VII (GSDVII), also known as Tarui's disease, can be diagnosed through various tests that assess the body's ability to break down glycogen in muscles.

• Blood tests: Blood tests can help identify abnormal levels of certain enzymes and metabolites associated with GSDVII. These include:
  • Elevated creatinine kinase (CK) levels [9]
  • High lactate dehydrogenase (LDH) levels [3]
  • Abnormal glucose and lactate levels after exercise [11]
• Genetic testing: Genetic testing can confirm the diagnosis of GSDVII by identifying mutations in the muscle phosphofructokinase (PFKM) gene. This test is considered a "gold standard" for diagnosing GSDVII [14].
• Muscle biopsy: A muscle biopsy can be performed to assess the level of glycogen accumulation and enzyme activity in muscle cells.
• Imaging studies: Imaging studies such as MRI scans may also be used to rule out other conditions that may present with similar symptoms.

It's worth noting that a combination of clinical presentation, biochemical tests, and genetic testing is often required for an accurate diagnosis of GSDVII. The diagnostic process can be complex, and consultation with a specialist in genetics or metabolic disorders is recommended.

References: [3] Ronquist G. Glycogenosis type VII (Tarui’s disease): diagnostic considerations and management. [9] How is glycogen storage disease diagnosed? [11] Clinical practice guidelines for glycogen storage disease V & VII (McArdle disease and Tarui disease) from an international study group [14] Abdenur JE, Eng CM, Desnick RJ. Molecular prenatal diagnosis of glycogen storage disease type Ia.

Current Drug Treatments for Glycogen Storage Disease Type VII

There are currently no specific drugs that can cure glycogen storage disease type VII (GSDVII). However, various treatments aim to alleviate symptoms and manage the condition. According to search results [7] and [8], one such treatment is Allopurinol, a medication capable of reducing uric acid levels in the blood, which may help control symptoms.

Other Potential Treatments

Research on dietary treatment for GSD VII has been limited [8]. Unlike GSD V, oral or intravenous supplements with sucrose or glucose are not recommended as they can be detrimental. However, further studies are needed to explore potential dietary interventions.

Enzyme Replacement Therapy (ERT)

While ERT is available for some glycogen storage diseases, its effectiveness in treating GSD VII specifically has not been extensively studied [9]. Myozyme (alglucosidase alfa) is a commercially available option for enzyme replacement therapy, but it may not be directly applicable to GSDVII.

Clinical Practice Guidelines

Recent clinical practice guidelines for glycogen storage disease V & VII have been published by an international study group [11] and [14]. These guidelines provide valuable insights into the current best practices for diagnosis and management of these conditions. However, specific drug treatments for GSDVII are not extensively discussed in these guidelines.

Emerging Therapies

Research on novel therapies, such as antibody-enzyme fusion (AEF) platforms, is underway to treat glycogen storage disorders [13]. These emerging technologies may hold promise for future treatment options, including those for GSD VII.

Glycogen storage disease type VII (GSD VII), also known as Tarui disease, is a rare genetic disorder that affects the muscles and red blood cells. The differential diagnosis for GSD VII involves distinguishing it from other conditions that present with similar symptoms.

Similar Conditions:

• Glycogen storage disease type VIII: This condition also presents with muscle cramps, anemia, and increased levels of uric acid.
• McArdle disease (Glycogen storage disease type V): This condition is characterized by exercise intolerance, muscle cramping, and exertional myopathy, but it does not involve compensated hemolysis.

Key Features to Distinguish GSD VII:

• Compensated Hemolysis: GSD VII is distinguished from other glycogen storage diseases by the presence of compensated hemolysis, which refers to a mild increase in red blood cell turnover without significant anemia.
• Muscle Cramps with Exercise: Muscle cramps and exercise intolerance are common symptoms of GSD VII, but they can also be present in other conditions.
• Anemia: Anemia is a feature of GSD VII, but it is not as severe as in some other glycogen storage diseases.

Diagnostic Criteria:

To diagnose GSD VII, the following criteria should be met:

1. Presence of compensated hemolysis
2. Muscle cramps and exercise intolerance
3. Anemiaisocytosis (variation in red blood cell size)
4. Absence of significant anemia

References:

• [6] Glycogen storage diseases (GSDs), also referred to as glycogenoses, are inherited metabolic disorders of glycogen metabolism caused by deficiency of enzymes or transporters involved in the synthesis or degradation of glycogen leading to aberrant storage and/or utilization.
• [13] Glycogen storage disease VII is an autosomal recessive metabolic disorder characterized clinically by exercise intolerance, muscle cramping, exertional myopathy, and compensated hemolysis. Myoglobinuria may also occur.
• [15] Type VII- Tarui's Disease. Muscle cramps with exercise; Anemia.

Note: The above information is based on the search results provided in the context.