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Pompe disease
Also known as Pompe disease (infantile) · Pompe disease (late-onset)
This inherited disorder results in progressive muscle weakness and can affect various organ systems, including the heart and respiratory muscles. It impacts individuals from infancy through adulthood, with severity varying based on the age of onset.
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Overview
Pompe disease, also known as glycogen storage disease type II, is an inherited metabolic disorder where the body cannot properly break down glycogen, a stored form of glucose [PMID:33678082]. This inability leads to an accumulation of glycogen within cellular compartments called lysosomes, particularly in muscle cells throughout the body [PMID:24268686]. The build-up of glycogen causes damage to these cells, resulting in progressive muscle weakness and other related health problems.
The condition is rare, affecting approximately 1 in 40,000 individuals, though prevalence can vary between different populations. Pompe disease can manifest at any age, from infancy to late adulthood, and the age of onset often correlates with the severity and specific symptoms experienced. Early diagnosis and management can help slow disease progression and improve quality of life.
Symptoms & clinical features
The symptoms of Pompe disease can vary significantly, depending on whether it begins in infancy or later in life. Infantile-onset Pompe disease typically presents within the first few months of life and is often the most severe form. Infants may experience significant muscle weakness (hypotonia), which can lead to difficulties with feeding, poor weight gain, and delayed motor development, such as not reaching milestones like sitting or standing [PMID:24268686]. A common and serious symptom in infants is hypertrophic cardiomyopathy, where the heart muscle becomes abnormally thick, impairing its function [PMID:33678082]. Respiratory difficulties due to weak breathing muscles are also frequently observed.
Late-onset Pompe disease can appear in childhood, adolescence, or adulthood. Symptoms tend to be more gradual and varied, primarily involving progressive weakness of the skeletal muscles, especially those in the hips, shoulders, and trunk. This weakness can cause problems with walking, climbing stairs, and lifting objects. Respiratory muscle weakness, leading to breathing difficulties, particularly during sleep, is also a common feature. Some individuals may experience fatigue, headaches, and an enlarged liver. The progression of symptoms can vary considerably among individuals with late-onset disease.
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Affected organs
Pompe disease primarily affects the muscles throughout the body. In infantile-onset forms, the heart muscle is significantly impacted, leading to hypertrophic cardiomyopathy. Skeletal muscles, responsible for movement, are affected in both infantile and late-onset forms. This includes muscles in the limbs, trunk, and the diaphragm, which is crucial for breathing.
The respiratory system is often compromised due to the weakness of breathing muscles, which can lead to sleep-disordered breathing and recurrent respiratory infections. In some cases, the liver can become enlarged due to glycogen accumulation.
Risks & severity
The severity of Pompe disease exists on a spectrum, primarily categorised by the age of symptom onset. Infantile-onset Pompe disease is generally the most severe, with rapid progression of muscle weakness and significant heart involvement. Without timely intervention, infants with this form often experience severe complications, including heart failure and respiratory failure, which can be life-threatening within the first year of life.
Late-onset Pompe disease is typically less severe and progresses more slowly. The age of onset can range from childhood to adulthood, and symptoms are primarily characterised by progressive weakness of the skeletal muscles and respiratory muscles. The rate of progression can differ significantly between individuals, with some experiencing gradual decline over many years and others facing a more rapid worsening of symptoms. Respiratory complications, including reduced lung capacity and sleep-disordered breathing, are common and can become life-threatening over time if not managed.
Genetic causes
Pompe disease is caused by pathogenic variants in the GAA gene. This gene provides instructions for making an enzyme called acid alpha-glucosidase (GAA), also known as acid maltase [PMID:24268686]. The GAA enzyme plays a critical role in lysosomes, which are specialised compartments within cells that break down and recycle various substances. Specifically, the GAA enzyme is responsible for breaking down glycogen into a simpler sugar called glucose [PMID:33678082].
When there are pathogenic variants in the GAA gene, the enzyme is either deficient or completely absent. As a result, glycogen cannot be properly broken down within the lysosomes. This leads to a build-up of glycogen, particularly in muscle cells, causing damage and impairing their function. The specific variant in the GAA gene can influence the amount of functional enzyme produced, which often dictates the age of onset and severity of Pompe disease.
- GAA alpha glucosidaseThe GAA gene encodes the acid alpha-glucosidase enzyme, essential for glycogen breakdown within cellular lysosomes, with variants associated with Pompe disease.
Inheritance pattern
Pompe disease is inherited in an autosomal recessive pattern. This means that an individual must inherit two altered copies of the GAA gene, one from each parent, to develop the condition. If a person inherits only one altered copy and one normal copy, they are considered a 'carrier' but typically do not show symptoms of the disease.
When two carriers have children, there is a 25% (1 in 4) chance with each pregnancy that their child will inherit two altered copies of the gene and develop Pompe disease. There is a 50% (2 in 4) chance that the child will be a carrier like their parents, and a 25% (1 in 4) chance that the child will inherit two normal copies of the gene and will neither have the condition nor be a carrier.
When both parents are carriers, each child has a 25% chance of being affected, 50% of being a carrier, and 25% of being unaffected.
Subtypes & variants
This page covers Pompe disease as a single condition. Several distinct variants and clinical subtypes are recognised in the literature - they share the underlying biology and broad management approach, but differ in severity, age of onset, or causative gene:
- Infantile-onset OMIM 232300
Severe form presenting in the first months of life with hypotonia, hypertrophic cardiomyopathy, and respiratory failure. Without enzyme replacement therapy (alglucosidase alfa), survival beyond the first year is rare. Newborn screening is now standard in many regions.
- Late-onset OMIM 232300
Slower-progressing form presenting in childhood through adulthood with proximal muscle weakness and respiratory muscle involvement. Cardiac involvement is uncommon. Enzyme replacement therapy slows progression.
Diagnosis & testing
Diagnosing Pompe disease typically involves a combination of clinical evaluation, biochemical tests, and genetic testing. If symptoms suggest Pompe disease, a doctor may first conduct a blood test to measure the activity of the acid alpha-glucosidase (GAA) enzyme in dried blood spots or other blood cells. Reduced or absent enzyme activity is a strong indicator of the condition.
Confirmation of a Pompe disease diagnosis is generally achieved through genetic testing of the GAA gene. This testing looks for specific pathogenic variants that are known to cause the disease. Referral to an NHS clinical genetics service may be made if Pompe disease is suspected. The NHS Genomic Medicine Service provides comprehensive genetic testing, and relevant R-codes (NHS test directory codes) for this testing would be determined by the clinical genetics team based on the specific presentation.
Management & lifestyle
Management of Pompe disease focuses on enzyme replacement therapy (ERT) and supportive care to address symptoms. ERT involves intravenously administering a manufactured version of the GAA enzyme, which helps to break down the accumulated glycogen in cells. This therapy can help to reduce glycogen build-up, improve muscle function, and, in infantile-onset cases, improve heart function and survival [PMID:33678082]. ERT is usually a lifelong treatment and is typically accessed through specialist NHS centres.
Supportive care is crucial and may include physiotherapy to maintain muscle strength and flexibility, respiratory support (such as non-invasive ventilation) for breathing difficulties, and nutritional support for feeding issues. Regular monitoring of heart function, respiratory function, and overall muscle strength is part of the ongoing management plan. Individuals and families are often supported by multidisciplinary teams, including paediatricians or adult physicians, neurologists, respiratory specialists, cardiologists, dietitians, and genetic counsellors.
UK care pathway
In the UK, suspected cases of Pompe disease are typically referred to specialist centres, often through the NHS Genomic Medicine Service (GMS). If a genetic condition like Pompe disease is suspected, a GP or specialist can refer patients to a clinical genetics service. These services provide expert assessment, diagnosis, and access to appropriate genetic testing under NHS R-codes. Genetic counsellors within these services offer information, support, and guidance on the implications of a diagnosis for individuals and their families, including inheritance patterns and family planning.
Frequently asked questions
What is the difference between infantile and late-onset Pompe disease?
Infantile-onset Pompe disease appears in the first few months of life, is generally more severe, and often includes significant heart problems. Late-onset Pompe disease can appear at any age from childhood to adulthood, typically progresses more slowly, and primarily affects skeletal and respiratory muscles, with less common heart involvement.
How is Pompe disease diagnosed?
Diagnosis usually involves a blood test to measure the activity of the GAA enzyme. If enzyme activity is low, genetic testing of the GAA gene is performed to identify pathogenic variants and confirm the diagnosis.
Is there a treatment for Pompe disease?
Yes, enzyme replacement therapy (ERT) is available. This treatment provides a manufactured version of the missing GAA enzyme to help break down glycogen. It is typically administered intravenously and is a lifelong treatment.
If I have Pompe disease, will my children also have it?
Pompe disease is inherited in an autosomal recessive pattern. If you have the condition, it means you have two altered copies of the GAA gene. Your children would inherit one altered copy from you. If your partner is also a carrier or has the condition, there would be a risk of your children inheriting two altered copies.
Can carriers of Pompe disease have symptoms?
Individuals who are carriers for Pompe disease typically do not experience symptoms. They have one working copy of the GAA gene, which is usually sufficient to produce enough enzyme for normal glycogen breakdown. Genetic counselling can provide more information for carriers.
References
- Taverna S, Cammarata G, Colomba P. Pompe disease: pathogenesis, molecular genetics and diagnosis. Aging. 2020. PMID: 32745073
- Milisenda JC, Matas-García A. Pompe disease. Medicina clinica. 2025. PMID: 40215906
- Kohler L, Puertollano R, Raben N. Pompe Disease: From Basic Science to Therapy. Neurotherapeutics : the journal of the American Society for Experimental NeuroTherapeutics. 2018. PMID: 30117059
- Meena NK, Raben N. Pompe Disease: New Developments in an Old Lysosomal Storage Disorder. Biomolecules. 2020. PMID: 32962155
- Kishnani PS, Steiner RD, Bali D. Pompe disease diagnosis and management guideline. Genetics in medicine : official journal of the American College of Medical Genetics. 2006. PMID: 16702877
- Schoser B. Pompe disease: what are we missing? Annals of translational medicine. 2019. PMID: 31392204
- Teener JW. Late-onset Pompe's disease. Seminars in neurology. 2012. PMID: 23677658
- Chien YH, Hwu WL, Lee NC. Newborn screening: Taiwanese experience. Annals of translational medicine. 2019. PMID: 31392193