Summary about Disease
Glycogen storage disease type II (GSD II), also known as Pompe disease, is a rare, inherited metabolic disorder. It is caused by a deficiency or absence of the lysosomal enzyme acid alpha-glucosidase (GAA). This enzyme is essential for breaking down glycogen, a stored form of sugar, within the lysosomes of cells. Without sufficient GAA, glycogen accumulates in various tissues and organs, especially muscles, leading to progressive muscle weakness (myopathy) and organ damage. Pompe disease can manifest at different ages with varying degrees of severity.
Symptoms
Symptoms vary depending on the age of onset.
Infantile-onset Pompe disease: This is the most severe form. Symptoms typically appear within the first few months of life and include:
Profound muscle weakness (hypotonia)
Cardiomegaly (enlarged heart)
Feeding difficulties
Failure to thrive
Respiratory problems
Macroglossia (enlarged tongue)
Late-onset Pompe disease: Symptoms develop later in infancy, childhood, adolescence, or adulthood. These may include:
Progressive muscle weakness, particularly in the legs and trunk
Breathing difficulties
Exercise intolerance
Lordosis (inward curvature of the lower back)
Fatigue
Difficulty walking or running
Frequent respiratory infections
Causes
Pompe disease is caused by mutations in the GAA gene. This gene provides instructions for making the acid alpha-glucosidase (GAA) enzyme. These mutations lead to a deficiency or complete absence of functional GAA enzyme. Pompe disease is inherited in an autosomal recessive pattern, meaning that an individual must inherit two copies of the mutated gene (one from each parent) to develop the disease. Individuals who inherit only one copy of the mutated gene are carriers and usually do not show symptoms of the disease.
Medicine Used
The primary treatment for Pompe disease is enzyme replacement therapy (ERT).
Alglucosidase alfa (Myozyme/Lumizyme): This medication provides a synthetic form of the GAA enzyme, which helps to break down the accumulated glycogen in cells. ERT is administered intravenously and is a lifelong therapy. Other treatments may include supportive care:
Physical therapy
Occupational therapy
Respiratory support
Nutritional support
Is Communicable
No, Pompe disease is not communicable. It is a genetic disorder caused by inherited gene mutations, not by an infectious agent.
Precautions
There are no specific precautions to prevent contracting Pompe disease since it is a genetic condition. For individuals with Pompe disease, precautions include:
Adhering to prescribed enzyme replacement therapy and supportive care.
Regular monitoring of cardiac and respiratory function.
Avoiding activities that excessively strain weakened muscles.
Receiving vaccinations to prevent respiratory infections.
Consulting with a multidisciplinary team of healthcare professionals for optimal management.
How long does an outbreak last?
Pompe disease is not an outbreak, it is a chronic condition, its duration is lifelong.
How is it diagnosed?
Pompe disease can be diagnosed through several methods:
Enzyme assay: This test measures the activity of the GAA enzyme in blood, skin fibroblasts, or muscle tissue. Low or absent GAA activity indicates Pompe disease.
Genetic testing: This test analyzes the GAA gene for mutations. Identifying two disease-causing mutations confirms the diagnosis.
Muscle biopsy: A small sample of muscle tissue is examined under a microscope to look for glycogen accumulation.
Newborn screening: In some regions, newborns are screened for Pompe disease using a blood test to measure GAA enzyme activity.
Timeline of Symptoms
Infantile-onset: Symptoms typically appear within the first few months of life, including muscle weakness, cardiomegaly, feeding difficulties, and respiratory problems.
Late-onset: The timeline of symptoms can vary considerably. Symptoms may emerge in later infancy, childhood, adolescence, or adulthood. Initial symptoms often include progressive muscle weakness, breathing difficulties, and exercise intolerance. Symptoms gradually worsen over time. The progression of symptoms is highly variable among individuals with late-onset Pompe disease.
Important Considerations
Early diagnosis and treatment are crucial for improving outcomes, especially in infantile-onset Pompe disease.
Enzyme replacement therapy is not a cure but can help to slow the progression of the disease and improve muscle function and overall survival.
Supportive care is essential for managing symptoms and improving quality of life.
Genetic counseling is recommended for families with a history of Pompe disease to assess the risk of having affected children.
Multidisciplinary care involving specialists such as neurologists, cardiologists, pulmonologists, physical therapists, and geneticists is important for comprehensive management.
Clinical trials are ongoing to evaluate new treatments and therapies for Pompe disease.