Summary about Disease
Acid maltase deficiency (AMD), also known as Pompe disease or glycogen storage disease type II (GSD II), is a rare, inherited metabolic disorder caused by a deficiency of the lysosomal enzyme acid alpha-glucosidase (GAA). This enzyme is responsible for breaking down glycogen, a stored form of sugar, in the lysosomes of cells. When GAA is deficient, glycogen accumulates in various tissues and organs, particularly muscles, leading to progressive muscle weakness and other complications. The severity and age of onset vary, leading to classifications of infantile-onset, late-onset (childhood/juvenile), and adult-onset Pompe disease.
Symptoms
Symptoms vary depending on the age of onset.
Infantile-onset: Severe muscle weakness (hypotonia), feeding difficulties, failure to thrive, enlarged heart (cardiomyopathy), enlarged tongue (macroglossia), respiratory problems, and liver enlargement. Without treatment, most infants die within the first year of life.
Late-onset (childhood/juvenile/adult): Progressive muscle weakness, primarily affecting the limb and respiratory muscles, difficulty breathing, fatigue, exercise intolerance, progressive walking difficulties, scoliosis, and respiratory infections. Cardiomyopathy is rare in late-onset forms.
Causes
Pompe disease is caused by mutations in the GAA gene, which provides instructions for making the acid alpha-glucosidase enzyme. These mutations result in a deficiency or complete absence of the functional enzyme. It is inherited in an autosomal recessive pattern, meaning that both parents must carry a copy of the mutated gene for their child to be affected.
Medicine Used
The primary treatment for Pompe disease is enzyme replacement therapy (ERT) with recombinant human GAA (rhGAA), such as alglucosidase alfa (Myozyme) or avalglucosidase alfa (Nexviazyme). ERT helps to replace the deficient enzyme and reduce glycogen accumulation in tissues. Supportive therapies, such as physical therapy, occupational therapy, and respiratory support (e.g., mechanical ventilation), are also crucial for managing symptoms and improving quality of life.
Is Communicable
Pompe disease is not communicable. It is a genetic disorder caused by inherited gene mutations and cannot be transmitted from person to person through any infectious means.
Precautions
There are no specific precautions to prevent getting Pompe disease, as it is a genetic disorder. Genetic counseling and testing are recommended for individuals with a family history of Pompe disease who are planning to have children. For individuals diagnosed with Pompe disease, precautions focus on managing symptoms, preventing complications, and optimizing quality of life. These include:
Following prescribed treatment regimens (ERT).
Engaging in regular physical therapy and exercise programs as recommended by healthcare professionals.
Managing respiratory problems with appropriate interventions (e.g., assisted ventilation, cough assist devices).
Avoiding activities that may overstress weakened muscles.
Receiving vaccinations against respiratory infections.
Maintaining a healthy diet and weight.
Regular monitoring of cardiac and respiratory function.
How long does an outbreak last?
Pompe disease is not an infectious disease, so the term "outbreak" is not applicable. It is a chronic, progressive condition that persists throughout the affected individual's life. The duration of symptoms and the rate of disease progression vary depending on the age of onset and the severity of the enzyme deficiency.
How is it diagnosed?
Diagnosis of Pompe disease involves:
Clinical evaluation: Assessment of symptoms and medical history.
Enzyme assay: Measurement of GAA enzyme activity in blood (dried blood spot testing), muscle biopsy, or cultured fibroblasts. Low GAA activity indicates Pompe disease.
Genetic testing: Analysis of the GAA gene to identify mutations.
Muscle biopsy: Examination of muscle tissue to detect glycogen accumulation.
Newborn screening: In some regions, Pompe disease is included in newborn screening programs, allowing for early diagnosis and treatment initiation.
Timeline of Symptoms
Infantile-onset: Symptoms typically appear within the first few months of life.
Late-onset (childhood/juvenile): Symptoms may appear in childhood or adolescence.
Adult-onset: Symptoms typically appear in adulthood, often between the ages of 20 and 60. The progression of symptoms is variable, even within the same age group. Generally, infantile-onset is the most rapidly progressive, while adult-onset tends to progress more slowly.
Important Considerations
Early diagnosis and treatment are crucial to improve outcomes, especially in infantile-onset Pompe disease.
Enzyme replacement therapy (ERT) is the mainstay of treatment and can significantly improve muscle function and prolong survival.
Supportive therapies, such as physical therapy and respiratory support, are essential for managing symptoms and improving quality of life.
Genetic counseling is recommended for families affected by Pompe disease to assess the risk of recurrence in future pregnancies.
Continuous monitoring by a multidisciplinary team of healthcare professionals is necessary to manage the disease effectively.
Individuals with Pompe disease and their families should have access to support groups and resources.