Pompe Disease

Mendelian MONDO:0009290 Pathograph 32 Glycogen Storage Disease Lysosomal Storage Disease

Pompe disease (glycogen storage disease type II, acid maltase deficiency) is an autosomal recessive lysosomal storage disorder caused by deficiency of acid alpha-glucosidase (GAA), the enzyme responsible for lysosomal glycogen degradation. GAA deficiency leads to progressive glycogen accumulation in lysosomes, particularly in skeletal muscle, cardiac muscle, and smooth muscle. The disease spans a clinical continuum from severe infantile-onset Pompe disease (IOPD), characterized by hypertrophic cardiomyopathy, generalized hypotonia, and death within the first year if untreated, to late-onset Pompe disease (LOPD), presenting with progressive proximal myopathy and respiratory insufficiency. Enzyme replacement therapy with recombinant human GAA (alglucosidase alfa, avalglucosidase alfa) has transformed outcomes, particularly in IOPD when initiated early.

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Mappings

Differentials

Datasets

Trials

Models

References

Deep Research

🏷

Classifications

Harrison's Chapter

Lysosomal Storage

📘

Definitions

Orphanet disease definition

Orphanet defines Pompe disease as a rare lysosomal storage disease with infantile-onset and late-onset forms, characterized by lysosomal glycogen accumulation in skeletal, cardiac, and respiratory muscles.

CASE_DEFINITION

Show evidence (1 reference)

ORPHA:365 SUPPORT Other

"A rare lysosomal storage disease characterized by lysosomal accumulation of glycogen particularly in skeletal, cardiac, and respiratory muscles, as well as the liver and nervous system, due to acid maltase deficiency. The clinical spectrum comprises infantile-onset disease with severe..."

Orphanet's definition supports the multisystem lysosomal storage disease framing of this entry.

👪

Inheritance

Autosomal recessive HP:0000007

Pompe disease is inherited in an autosomal recessive manner. Affected individuals carry biallelic pathogenic variants in the GAA gene. Carrier frequency is estimated at approximately 1 in 100-200 in most populations. Disease incidence varies by population, estimated at approximately 1 in 40,000 overall.

Autosomal recessive inheritance

Show evidence (2 references)

PMID:18929906 SUPPORT Human Clinical

"It is a pan-ethnic autosomal recessive trait characterised by acid alpha-glucosidase deficiency leading to lysosomal glycogen storage."

The Lancet review by van der Ploeg and Reuser establishes Pompe disease as an autosomal recessive trait.

ORPHA:365 SUPPORT Other

"Autosomal recessive"

Orphanet records autosomal recessive inheritance for Pompe disease.

◆

Subtypes

Infantile-onset Pompe disease (IOPD)

Classic infantile-onset form presenting within the first few months of life with hypertrophic cardiomyopathy, profound hypotonia (floppy infant), feeding difficulties, failure to thrive, hepatomegaly, and macroglossia. Without treatment, death typically occurs from cardiorespiratory failure before age 1-2 years. Residual GAA enzyme activity is usually less than 1%.

Late-onset Pompe disease (LOPD)

Encompasses childhood, juvenile, and adult-onset forms presenting with progressive proximal and limb-girdle muscle weakness, respiratory insufficiency, and elevated creatine kinase. Cardiac involvement is typically absent or minimal. Residual GAA enzyme activity is usually 1-30%. Symptoms may present from early childhood to late adulthood depending on residual enzyme activity.

⚙

Pathophysiology

Lysosomal glycogen accumulation

Deficiency of acid alpha-glucosidase (GAA) prevents normal lysosomal degradation of glycogen. Glycogen progressively accumulates within lysosomes, establishing the substrate-storage lesion that drives downstream autophagic, skeletal muscle, respiratory muscle, and cardiac pathology.

Skeletal muscle fiber link Cardiac muscle cell link

Glycogen catabolic process link Lysosome organization link

Downstream

Autophagy dysregulation Glycogen-overloaded lysosomes perturb lysosome-dependent autophagic flux in muscle.

Skeletal and respiratory myofiber injury Glycogen storage in skeletal and respiratory muscles disrupts contractile tissue and respiratory mechanics.

Cardiomyocyte glycogen storage and hypertrophic remodeling Glycogen storage in cardiomyocytes drives the hypertrophic cardiac phenotype of infantile-onset disease.

Hepatomegaly Lysosomal glycogen storage in infantile-onset disease can involve liver enlargement.

Macroglossia Glycogen storage in tongue musculature contributes to macroglossia in infantile-onset disease.

Hearing impairment The broader lysosomal-storage phenotype includes hearing impairment in a minority of Pompe patients.

Thoracic aortic aneurysm In late-onset disease, systemic glycogen-storage pathology can include adult arteriopathy with ascending thoracic aortic dilatation.

Show evidence (2 references)

PMID:32745073 SUPPORT Human Clinical

"GAA catalyzes the hydrolysis of α-1,4 and α-1,6-glucosidic bonds of glycogen and its deficiency leads to lysosomal storage of glycogen in several tissues, particularly in muscle."

Taverna et al. review confirms that GAA deficiency leads to lysosomal glycogen storage predominantly in muscle tissue.

PMID:18929906 SUPPORT Human Clinical

"acid alpha-glucosidase deficiency leading to lysosomal glycogen storage"

The Lancet review establishes the core pathogenic mechanism of GAA deficiency causing lysosomal glycogen accumulation.

Autophagy dysregulation

Beyond glycogen accumulation, Pompe disease involves profound dysregulation of autophagy. Autophagic buildup in type II muscle fibers represents a major pathological feature in both IOPD and LOPD. Impaired autophagosome-lysosome fusion leads to accumulation of autophagic debris, which can be as destructive to muscle architecture as glycogen storage itself. This autophagic pathology may limit the effectiveness of enzyme replacement therapy.

Skeletal muscle fiber link

Autophagy link

Downstream

Skeletal and respiratory myofiber injury Autophagic buildup and impaired lysosomal delivery contribute to progressive muscle fiber damage.

Show evidence (2 references)

PMID:20040311 SUPPORT Model Organism

"In the GAA-knockout mouse model, progressive accumulation of autophagic vesicles is restricted to Type II-rich muscle fibers. Not only does this build-up of autophagosomes disrupt the contractile apparatus in the muscle fibers, it also interferes with enzyme replacement therapy by acting as a..."

Shea and Raben demonstrated in GAA-knockout mice that autophagic buildup disrupts muscle architecture and impairs ERT efficacy by preventing enzyme delivery to lysosomes.

PMID:38785980 SUPPORT Human Clinical

"The autophagic pathway is largely responsible for the delivery of cytosolic glycogen to the lysosome where it is degraded to glucose via acid α-glucosidase."

Do, Meena, and Raben review links lysosome-dependent autophagy to glycogen delivery and acid alpha-glucosidase-dependent degradation.

Skeletal and respiratory myofiber injury

Glycogen storage and autophagic debris injure skeletal and respiratory muscle fibers, producing progressive limb-girdle weakness, exercise intolerance, and respiratory insufficiency.

Skeletal muscle fiber link

Downstream

Progressive proximal myopathy Skeletal muscle fiber injury clinically manifests as progressive proximal and limb-girdle weakness.

Respiratory insufficiency Respiratory myofiber injury weakens ventilatory muscles and causes respiratory insufficiency.

Generalized hypotonia Infantile Pompe myofiber injury manifests as hypotonia and generalized muscle weakness.

Failure to thrive Feeding difficulty and poor growth follow from severe infantile muscle and respiratory involvement.

Motor delay Muscle weakness and hypotonia delay acquisition of motor milestones in infantile Pompe disease.

Elevated creatine kinase Ongoing skeletal muscle injury releases creatine kinase into circulation.

Exercise intolerance Progressive limb-girdle and respiratory myofiber injury limits sustained activity.

Fatigue Progressive skeletal and respiratory muscle involvement contributes to chronic fatigue.

Dysphagia Oropharyngeal and esophageal muscle weakness can impair swallowing.

Scoliosis Axial and paraspinal muscle weakness contributes to scoliosis.

Recurrent respiratory infections Respiratory muscle weakness and impaired airway clearance predispose to recurrent respiratory infections.

Show evidence (2 references)

PMID:32745073 SUPPORT Human Clinical

"PD is a chronic and progressive pathology usually characterized by limb-girdle muscle weakness and respiratory failure."

Directly supports the downstream myofiber-injury phenotype of limb-girdle weakness and respiratory failure.

PMID:32505193 SUPPORT Human Clinical

"The GAA deficiency results into glycogen accumulation, especially in fibers of skeletal, respiratory and cardiac muscles; the consequence is a progressive invalidating disease"

Supports injury of skeletal and respiratory muscle fibers as a consequence of GAA-deficiency-driven glycogen accumulation.

Cardiomyocyte glycogen storage and hypertrophic remodeling

In infantile-onset Pompe disease, cardiomyocyte glycogen storage produces cardiac hypertrophy and hypertrophic cardiomyopathy that contribute to early cardiorespiratory morbidity when untreated.

Cardiac muscle cell link

Cardiac muscle hypertrophy link ↑ INCREASED

Downstream

Hypertrophic cardiomyopathy Cardiomyocyte glycogen storage and hypertrophic remodeling produce the infantile-onset hypertrophic cardiomyopathy phenotype.

Shortened PR interval Glycogen deposition in cardiac conduction tissue causes conduction defects with shortened PR interval in infantile-onset Pompe disease.

Show evidence (2 references)

PMID:18929906 SUPPORT Human Clinical

"Cardiac hypertrophy is a key feature of classic infantile Pompe's disease."

Supports cardiac hypertrophy as a key infantile-onset consequence of Pompe disease.

PMID:17151339 SUPPORT Human Clinical

"Infantile-onset Pompe disease is characterized by cardiomyopathy, respiratory and skeletal muscle weakness, and early death."

Supports cardiomyopathy as part of the infantile-onset Pompe disease phenotype.

✶

Histopathology

Glycogen accumulation in muscle fiber lysosomes FREQUENT

Muscle pathology in Pompe disease includes lysosomal glycogen accumulation within muscle fibers, corresponding to the storage lesion caused by deficient lysosomal acid alpha-glucosidase activity.

Show evidence (1 reference)

ORPHA:365 SUPPORT Other

"HP:0030231 | Glycogen accumulation in muscle fiber lysosomes | Frequent (79-30%)"

Orphanet records glycogen accumulation in muscle fiber lysosomes as a frequent Pompe disease finding.

⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.

●

Phenotypes

Cardiovascular 1

Hypertrophic cardiomyopathy HP_0040281 Hypertrophic cardiomyopathy (HP:0001639)

Show evidence (3 references)

PMID:18929906 SUPPORT Human Clinical

"Cardiac hypertrophy is a key feature of classic infantile Pompe's disease."

The Lancet review confirms cardiac hypertrophy as a key feature of classic infantile Pompe disease.

ORPHA:365 SUPPORT Other

"HP:0001639 | Hypertrophic cardiomyopathy | Occasional (29-5%)"

Orphanet classifies hypertrophic cardiomyopathy as Occasional across the full Pompe disease spectrum; frequency is higher in IOPD specifically.

PMID:17151339 SUPPORT Human Clinical

"Infantile-onset Pompe disease is characterized by cardiomyopathy, respiratory and skeletal muscle weakness, and early death."

The Kishnani et al. clinical trial paper confirms cardiomyopathy as a characteristic feature of infantile-onset Pompe disease.

Digestive 2

Hepatomegaly HP_0040282 Hepatomegaly (HP:0002240)

Show evidence (2 references)

PMID:26889246 SUPPORT Human Clinical

"a newborn who was found to have cardiac hypertrophy, hepatomegaly and elevated serum enzyme levels"

Liu et al. case report documents hepatomegaly as a presenting feature of infantile Pompe disease.

ORPHA:365 SUPPORT Other

"HP:0002240 | Hepatomegaly | Frequent (79-30%)"

Orphanet classifies hepatomegaly as Frequent (79-30%) in Pompe disease.

Dysphagia HP_0040283 Dysphagia (HP:0002015)

Show evidence (1 reference)

ORPHA:365 SUPPORT Other

"HP:0002015 | Dysphagia | Occasional (29-5%)"

Orphanet classifies dysphagia as Occasional (29-5%) in Pompe disease.

Ear 1

Hearing impairment HP_0040283 Hearing impairment (HP:0000365)

Show evidence (1 reference)

ORPHA:365 SUPPORT Other

"HP:0000365 | Hearing impairment | Occasional (29-5%)"

Orphanet classifies hearing impairment as Occasional (29-5%) in Pompe disease.

Head and Neck 1

Macroglossia HP_0040283 Macroglossia (HP:0000158)

Show evidence (2 references)

PMID:39020349 SUPPORT Human Clinical

"presented with generalized hypotonia, macroglossia, hyporeflexia, and mild left ventricular hypertrophy"

Castellar-Leones et al. case report documents macroglossia as a presenting feature in an infant with early-onset Pompe disease.

ORPHA:365 SUPPORT Other

"HP:0000158 | Macroglossia | Occasional (29-5%)"

Orphanet classifies macroglossia as Occasional (29-5%) across the full Pompe disease spectrum.

Immune 1

Recurrent respiratory infections HP_0040282 Recurrent respiratory infections (HP:0002205)

Show evidence (1 reference)

ORPHA:365 SUPPORT Other

"HP:0002205 | Recurrent respiratory infections | Frequent (79-30%)"

Orphanet classifies recurrent respiratory infections as Frequent (79-30%) in Pompe disease.

Metabolism 1

Elevated creatine kinase HP_0040282 Elevated circulating creatine kinase concentration (HP:0003236)

Show evidence (2 references)

PMID:26889246 SUPPORT Human Clinical

"cardiac hypertrophy, hepatomegaly and elevated serum enzyme levels, which was characterized by an aspartate aminotransferase level of 95 U/l, lactate dehydrogenase level of 778 U/l and creatine kinase level of 1,299 U/l"

Liu et al. case report documents markedly elevated creatine kinase (1,299 U/l) in an infant with Pompe disease, consistent with ongoing muscle damage.

ORPHA:365 SUPPORT Other

"HP:0003236 | Elevated circulating creatine kinase concentration | Frequent (79-30%)"

Orphanet classifies elevated CK as Frequent (79-30%) in Pompe disease.

Musculoskeletal 4

Generalized hypotonia HP_0040281 Hypotonia (HP:0001252)

Show evidence (2 references)

PMID:33554498 SUPPORT Human Clinical

"Pompe disease manifests with a broad spectrum of disease severity, ranging from severe infantile-onset diseases such as hypotonia and hypertrophic cardiomyopathy to late-onset diseases such as myopathy and respiratory compromise."

Davison review confirms hypotonia as a key manifestation of severe infantile-onset Pompe disease.

ORPHA:365 SUPPORT Other

"HP:0008947 | Floppy infant | Occasional (29-5%)"

Orphanet annotates floppy infant as Occasional across the full disease spectrum; frequency is higher in IOPD specifically.

Progressive proximal myopathy HP_0040281 Proximal muscle weakness (HP:0003701)

Show evidence (2 references)

PMID:32745073 SUPPORT Human Clinical

"PD is a chronic and progressive pathology usually characterized by limb-girdle muscle weakness and respiratory failure."

Taverna et al. review confirms that Pompe disease is characterized by progressive limb-girdle muscle weakness.

ORPHA:365 SUPPORT Other

"HP:0009073 | Progressive proximal muscle weakness | Very frequent (99-80%)"

Orphanet classifies progressive proximal muscle weakness as Very frequent (99-80%) in Pompe disease.

Respiratory insufficiency HP_0040282 Respiratory insufficiency due to muscle weakness (HP:0002747)

Show evidence (2 references)

PMID:20393176 SUPPORT Human Clinical

"Late-onset Pompe's disease is characterized by progressive muscle weakness and loss of respiratory function, leading to early death."

The van der Ploeg et al. NEJM trial confirms progressive loss of respiratory function as characteristic of late-onset Pompe disease.

ORPHA:365 SUPPORT Other

"HP:0002747 | Respiratory insufficiency due to muscle weakness | Frequent (79-30%)"

Orphanet classifies respiratory insufficiency due to muscle weakness as Frequent (79-30%) in Pompe disease.

Scoliosis HP_0040283 Scoliosis (HP:0002650)

Show evidence (1 reference)

ORPHA:365 SUPPORT Other

"HP:0002650 | Scoliosis | Occasional (29-5%)"

Orphanet classifies scoliosis as Occasional (29-5%) in Pompe disease.

Nervous System 1

Motor delay HP_0040282 Motor delay (HP:0001270)

Show evidence (2 references)

PMID:39020349 SUPPORT Human Clinical

"Functional tests revealed motor development delay, generalized hypotonia, and positive anti-recombinant human acid alpha-glucosidase IgG antibody titers"

Castellar-Leones et al. case report documents motor development delay as a feature of early-onset Pompe disease.

ORPHA:365 SUPPORT Other

"HP:0001270 | Motor delay | Frequent (79-30%)"

Orphanet classifies motor delay as Frequent (79-30%) in Pompe disease.

Constitutional 2

Exercise intolerance HP_0040282 Exercise intolerance (HP:0003546)

Show evidence (1 reference)

ORPHA:365 SUPPORT Other

"HP:0003546 | Exercise intolerance | Frequent (79-30%)"

Orphanet classifies exercise intolerance as Frequent (79-30%) in Pompe disease.

Fatigue HP_0040282 Fatigue (HP:0012378)

Show evidence (1 reference)

ORPHA:365 SUPPORT Other

"HP:0012378 | Fatigue | Frequent (79-30%)"

Orphanet classifies fatigue as Frequent (79-30%) in Pompe disease.

Growth 1

Failure to thrive HP_0040282 Failure to thrive (HP:0001508)

Show evidence (2 references)

PMID:16737883 SUPPORT Human Clinical

"feeding difficulties (57%), and failure to thrive (53%) appeared after a median age of approximately 4.0 months"

Kishnani et al. natural history study of 168 IOPD patients found failure to thrive in 53% of cases.

ORPHA:365 SUPPORT Other

"HP:0001508 | Failure to thrive | Frequent (79-30%)"

Orphanet classifies failure to thrive as Frequent (79-30%) in Pompe disease.

Other 2

Shortened PR interval Shortened PR interval (HP:0005165)

Show evidence (1 reference)

PMID:20301438 SUPPORT Other

"Progressive deposition of glycogen results in conduction defects with shortening of the PR interval on EKG."

GeneReviews documents shortened PR interval as a conduction finding in untreated IOPD.

Thoracic aortic aneurysm Thoracic aortic aneurysm (HP:0012727)

Show evidence (1 reference)

PMID:20301438 SUPPORT Other

"Some adults have developed arteriopathy, including dilatation of the ascending thoracic aorta."

GeneReviews documents ascending thoracic aortic dilatation as an adult LOPD vascular complication.

🧬

Genetic Associations

GAA gene mutations (Causative)

Show evidence (2 references)

PMID:32745073 SUPPORT Human Clinical

"Currently, more than 560 mutations spread throughout GAA gene have been reported."

Taverna et al. review confirms the large number of pathogenic variants reported in the GAA gene.

CGGV:assertion_0554320e-6a8f-4c39-be7f-99959a8341ee-2019-01-23T170000.000Z SUPPORT Other

ClinGen classifies the GAA-glycogen storage disease II gene-disease relationship as definitive with autosomal recessive inheritance.

💊

Treatments

Enzyme replacement therapy (ERT)

Action: enzyme replacement or supplementation therapy MAXO:0000933

Intravenous infusion of recombinant human GAA is the standard of care for Pompe disease. Alglucosidase alfa (Myozyme/Lumizyme) was the first approved ERT (2006). Avalglucosidase alfa (Nexviazyme), a next-generation ERT with enhanced mannose-6-phosphate receptor binding, was approved in 2021 and shows improved skeletal muscle uptake. ERT significantly improves survival and cardiac outcomes in IOPD and stabilizes or improves respiratory and motor function in LOPD.

Mechanism Target:

MODULATES Lysosomal glycogen accumulation — Recombinant human GAA supplies the deficient lysosomal enzyme upstream of glycogen storage.

Show evidence (1 reference)

PMID:17151339 SUPPORT Human Clinical

"Recombinant human acid alpha-glucosidase is safe and effective for treatment of infantile-onset Pompe disease."

Clinical trial evidence supports rhGAA as enzyme replacement therapy for the upstream GAA deficiency.

Target Phenotypes: Hypertrophic cardiomyopathy ↗ Proximal muscle weakness ↗ Respiratory insufficiency due to muscle weakness ↗

Show evidence (3 references)

PMID:17151339 SUPPORT Human Clinical

"All patients (100%) survived to 18 months of age. A Cox proportional hazards analysis demonstrated that treatment reduced the risk of death by 99%, reduced the risk of death or invasive ventilation by 92%, and reduced the risk of death or any type of ventilation by 88%, as compared to an..."

The landmark Kishnani et al. clinical trial demonstrated that rhGAA ERT reduced risk of death by 99% in infantile-onset Pompe disease compared to untreated historical controls.

PMID:20393176 SUPPORT Human Clinical

"At 78 weeks, the estimated mean changes from baseline in the primary end points favored alglucosidase alfa (an increase of 28.1+/-13.1 m on the 6-minute walk test and an absolute increase of 3.4+/-1.2 percentage points in FVC; P=0.03 and P=0.006, respectively)."

The van der Ploeg et al. NEJM randomized controlled trial showed that alglucosidase alfa significantly improved walking distance and stabilized pulmonary function in late-onset Pompe disease.

PMID:34800399 SUPPORT Human Clinical

"We consider that this study provides evidence of clinically meaningful improvement with avalglucosidase alfa therapy over alglucosidase alfa in respiratory function, ambulation, and functional endurance, with no new safety signals reported."

The COMET phase 3 trial demonstrated that avalglucosidase alfa provided clinically meaningful improvements in respiratory function over alglucosidase alfa in late-onset Pompe disease.

Cipaglucosidase alfa plus miglustat

Action: Enzyme replacement therapy with enzyme stabilizer Ontology label: pharmacotherapy MAXO:0000058

Agent: cipaglucosidase alfa ↗ miglustat ↗

A two-component therapy combining cipaglucosidase alfa, a novel recombinant human acid alpha-glucosidase, with miglustat, an enzyme stabilizer that enhances intracellular delivery. FDA-approved in 2023 for adults with late-onset Pompe disease. The PROPEL phase 3 trial (125 patients) showed numerical improvements in 6-minute walk distance and respiratory function versus alglucosidase alfa, with benefits particularly in patients previously receiving ERT for more than 2 years.

Target Phenotypes: Proximal muscle weakness ↗ Respiratory insufficiency due to muscle weakness ↗

Show evidence (1 reference)

PMID:34800400 SUPPORT Human Clinical

"At week 52, mean change from baseline in 6-min walk distance was 20·8 m (SE 4·6) in the cipaglucosidase alfa plus miglustat group versus 7·2 m (6·6) in the alglucosidase alfa plus placebo group using last observation carried forward (between-group difference 13·6 m [95% CI -2·8 to 29·9])."

The PROPEL phase 3 trial showed a numerical improvement in 6-minute walk distance with cipaglucosidase alfa plus miglustat versus standard ERT, though the primary endpoint did not reach statistical superiority in the overall population.

Respiratory support

Action: artificial respiration MAXO:0000503

Non-invasive ventilation (BiPAP) or invasive mechanical ventilation may be required for respiratory insufficiency. Many LOPD patients require nocturnal ventilatory support, and some progress to continuous ventilator dependence.

Target Phenotypes: Respiratory insufficiency due to muscle weakness ↗

Show evidence (2 references)

PMID:22173792 SUPPORT Human Clinical

"A multidisciplinary team should be involved to properly treat the pulmonary, neuromuscular, orthopedic, and gastrointestinal elements of late-onset Pompe disease."

Consensus treatment recommendations support pulmonary management as a component of Pompe disease care.

PMID:39457174 SUPPORT Human Clinical

"RMT has potential to be integrated into the cardioplulmonary rehabilitation for patients with Pompe disease."

Supports respiratory muscle training as part of cardiopulmonary rehabilitation in Pompe disease.

Cardiac medication and anesthesia precautions

Action: supportive care MAXO:0000950

Cardiac medication and anesthesia planning require Pompe-specific caution. GeneReviews warns that digoxin, inotropes, diuretics, and afterload-reducing agents may worsen left ventricular outflow obstruction in some stages, and that anesthesia should be used only when necessary because cardiovascular and respiratory reserve may be limited.

Target Phenotypes: Hypertrophic cardiomyopathy ↗ Respiratory insufficiency due to muscle weakness ↗

Show evidence (2 references)

PMID:20301438 SUPPORT Other

"The use of digoxin, ionotropes, diuretics, and afterload-reducing agents may worsen left ventricular outflow obstruction"

GeneReviews lists cardiac drugs that may worsen left ventricular outflow obstruction.

PMID:20301438 SUPPORT Other

"Anesthesia should be used only when absolutely necessary because reduced cardiovascular return and underlying respiratory insufficiency pose significant risks."

GeneReviews documents anesthesia risk from combined cardiovascular and respiratory vulnerability.

Physical therapy and rehabilitation

Action: Physical therapy Ontology label: physical therapy MAXO:0000011

Structured physical therapy and rehabilitation programs help maintain mobility, prevent contractures, and optimize residual muscle function. Exercise programs should be tailored to avoid overexertion.

Target Phenotypes: Proximal muscle weakness ↗ Exercise intolerance ↗

Show evidence (1 reference)

PMID:31811531 SUPPORT Human Clinical

"Therefore, we evaluated the role of physical activity, therapeutic exercise, and pulmonary rehabilitation programs in order to promote an appropriate management of motor and respiratory dysfunctions and improve QoL in patients with LOPD."

Supports therapeutic exercise and rehabilitation programs for motor and respiratory dysfunction in late-onset Pompe disease.

Dietary management

Action: Dietary management Ontology label: dietary intervention MAXO:0000088

High-protein diet may help preserve muscle mass. In IOPD, specialized feeding support including nasogastric or gastrostomy feeding may be needed.

Mechanism Target:

MODULATES Skeletal and respiratory myofiber injury — High-protein diet combined with exercise is intended to support residual muscle function in late-onset Pompe disease.

Show evidence (1 reference)

PMID:32505193 SUPPORT Human Clinical

"Exercise training, particularly if combined with high-protein diet, could reverse this decrease and result in an improvement, which was accompanied by improved quality of life."

Clinical study supports diet-plus-exercise as a modifier of muscle function and quality of life.

Target Phenotypes: Proximal muscle weakness ↗ Exercise intolerance ↗

Show evidence (1 reference)

PMID:32505193 SUPPORT Human Clinical

"Exercise training, particularly if combined with high-protein diet, could reverse this decrease and result in an improvement, which was accompanied by improved quality of life."

Supports high-protein dietary intervention in combination with exercise for late-onset Pompe disease.

Genetic counseling

Action: genetic counseling MAXO:0000079

Genetic counseling for families with Pompe disease addresses autosomal recessive recurrence risk, carrier testing for relatives, and prenatal or preimplantation genetic testing once familial GAA variants are known.

Mechanism Target:

MODULATES GAA gene mutations — Counseling and reproductive testing are anchored to the family's causal GAA pathogenic variants.

Show evidence (1 reference)

PMID:20301438 SUPPORT Other

"molecular genetic carrier testing for at-risk relatives and prenatal/preimplantation genetic testing are possible."

GeneReviews supports carrier and prenatal/preimplantation testing once familial GAA variants are known.

Show evidence (1 reference)

PMID:20301438 SUPPORT Other

"Pompe disease is inherited in an autosomal recessive manner."

GeneReviews establishes the inheritance basis for Pompe disease genetic counseling.

🔬

Biochemical Markers

Decreased acid alpha-glucosidase activity (DECREASED)

Context: Deficient lysosomal acid alpha-glucosidase activity is the defining biochemical abnormality and can be assayed in dried blood spot or liquid blood samples.

Pathograph Readouts

Readout Of Lysosomal glycogen accumulation Negative Diagnostic

Decreased acid alpha-glucosidase activity reports the upstream enzymatic defect that permits lysosomal glycogen storage.

Show evidence (1 reference)

PMID:33554498 SUPPORT Human Clinical

"The diagnosis requires demonstration of deficiency of the lysosomal acid alpha-glucosidase enzyme"

Diagnostic review evidence identifies decreased GAA activity as the defining biochemical abnormality.

Show evidence (2 references)

PMID:33554498 SUPPORT Human Clinical

"The diagnosis requires demonstration of deficiency of the lysosomal acid alpha-glucosidase enzyme, which can be assayed in dried blood spot or liquid blood samples, together with supportive biomarker tests, and confirmed with molecular genetic analysis."

Directly supports decreased acid alpha-glucosidase activity as the diagnostic biochemical abnormality and names relevant assay sample types.

ORPHA:365 SUPPORT Other

"HP:0034932 | Decreased circulating acid maltase activity | Very frequent (99-80%)"

Orphanet records decreased circulating acid maltase activity as very frequent in Pompe disease.

Urine total glucotetrasaccharide (Hex4) (INCREASED)

Context: Urinary total glucotetrasaccharide (Hex4/Glc4) is a glycogen-derived biochemical biomarker used as an adjunct for Pompe disease diagnosis and longitudinal monitoring.

Pathograph Readouts

Readout Of Lysosomal glycogen accumulation Positive Diagnostic

Elevated urinary Glc4 reports increased glycogen turnover from lysosomal glycogen storage.

Show evidence (1 reference)

PMID:11078593 SUPPORT Human Clinical

"all the patients had elevated Glc(4) levels compared with age-matched controls."

Biomarker study demonstrates elevated Glc4 in enzymatically confirmed Pompe disease patients.

Show evidence (2 references)

PMID:11078593 SUPPORT Human Clinical

"all the patients had elevated Glc(4) levels compared with age-matched controls."

Supports increased urine/plasma Glc4 as a Pompe disease biomarker.

PMID:20301438 SUPPORT Other

"CK level, and urine total glucotetrasaccharide (Hex4) level."

GeneReviews includes urine total Hex4 in Pompe disease surveillance.

{ }

Source YAML

click to show

name: Pompe Disease
creation_date: '2026-03-08T00:00:00Z'
updated_date: '2026-05-18T13:41:46Z'
category: Mendelian
description: >
  Pompe disease (glycogen storage disease type II, acid maltase deficiency) is an
  autosomal recessive lysosomal storage disorder caused by deficiency of acid
  alpha-glucosidase (GAA), the enzyme responsible for lysosomal glycogen degradation.
  GAA deficiency leads to progressive glycogen accumulation in lysosomes, particularly
  in skeletal muscle, cardiac muscle, and smooth muscle. The disease spans a clinical
  continuum from severe infantile-onset Pompe disease (IOPD), characterized by
  hypertrophic cardiomyopathy, generalized hypotonia, and death within the first
  year if untreated, to late-onset Pompe disease (LOPD), presenting with progressive
  proximal myopathy and respiratory insufficiency. Enzyme replacement therapy with
  recombinant human GAA (alglucosidase alfa, avalglucosidase alfa) has transformed
  outcomes, particularly in IOPD when initiated early.
disease_term:
  preferred_term: Pompe disease
  term:
    id: MONDO:0009290
    label: glycogen storage disease II
classifications:
  harrisons_chapter:
  - classification_value: endocrine system disorder
    evidence:
    - reference: PMID:22173792
      reference_title: "Consensus treatment recommendations for late-onset Pompe disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Pompe disease is a rare, autosomal recessive disorder caused by deficiency of the glycogen-degrading lysosomal enzyme acid alpha-glucosidase."
      explanation: Supports classifying Pompe disease with metabolic-system disorders in the Harrison's chapter framework.
  lysosomal_storage_category:
    classification_value: disorder of glycogen metabolism
    evidence:
    - reference: ORPHA:365
      reference_title: "Glycogen storage disease due to acid maltase deficiency (Orphanet structured-database record)"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "A rare lysosomal storage disease characterized by lysosomal accumulation of glycogen particularly in skeletal, cardiac, and respiratory muscles"
      explanation: Supports the lysosomal-storage classification as a glycogen-accumulation disorder.
definitions:
- name: Orphanet disease definition
  definition_type: CASE_DEFINITION
  description: >
    Orphanet defines Pompe disease as a rare lysosomal storage disease with
    infantile-onset and late-onset forms, characterized by lysosomal glycogen
    accumulation in skeletal, cardiac, and respiratory muscles.
  evidence:
  - reference: ORPHA:365
    reference_title: "Glycogen storage disease due to acid maltase deficiency (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "A rare lysosomal storage disease characterized by lysosomal accumulation of glycogen particularly in skeletal, cardiac, and respiratory muscles, as well as the liver and nervous system, due to acid maltase deficiency. The clinical spectrum comprises infantile-onset disease with severe hypertrophic cardiomyopathy, generalized muscle weakness, poor feeding and failure to thrive, and respiratory insufficiency, and late-onset disease manifesting before or after twelve months of age without cardiomyopathy, with proximal muscle weakness and respiratory insufficiency."
    explanation: Orphanet's definition supports the multisystem lysosomal storage disease framing of this entry.
external_assertions:
- name: Orphanet Pompe disease record
  source: Orphanet
  assertion_type: Structured disease record
  external_id: ORPHA:365
  url: http://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=en&Expert=365
  description: >
    Orphanet structured record for Pompe disease (glycogen storage disease due
    to acid maltase deficiency), including curated cross-references to MONDO,
    ICD-10, ICD-11, OMIM, MeSH, MedDRA, and UMLS identifiers.
  evidence:
  - reference: ORPHA:365
    reference_title: "Glycogen storage disease due to acid maltase deficiency (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "MONDO:0009290 | Exact"
    explanation: The Orphanet cross-reference table exactly maps ORPHA:365 to MONDO:0009290.
  - reference: ORPHA:365
    reference_title: "Glycogen storage disease due to acid maltase deficiency (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "OMIM:232300 | Exact"
    explanation: The Orphanet cross-reference table exactly maps ORPHA:365 to OMIM:232300.
  - reference: ORPHA:365
    reference_title: "Glycogen storage disease due to acid maltase deficiency (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "ICD-10:E74.0 | Narrower"
    explanation: The Orphanet cross-reference table maps ORPHA:365 to ICD-10 E74.0 as a narrower match.
parents:
- Glycogen Storage Disease
- Lysosomal Storage Disease
has_subtypes:
- name: IOPD
  display_name: Infantile-onset Pompe disease (IOPD)
  description: >
    Classic infantile-onset form presenting within the first few months of life with
    hypertrophic cardiomyopathy, profound hypotonia (floppy infant), feeding
    difficulties, failure to thrive, hepatomegaly, and macroglossia. Without
    treatment, death typically occurs from cardiorespiratory failure before age 1-2
    years. Residual GAA enzyme activity is usually less than 1%.
- name: LOPD
  display_name: Late-onset Pompe disease (LOPD)
  description: >
    Encompasses childhood, juvenile, and adult-onset forms presenting with progressive
    proximal and limb-girdle muscle weakness, respiratory insufficiency, and elevated
    creatine kinase. Cardiac involvement is typically absent or minimal. Residual GAA
    enzyme activity is usually 1-30%. Symptoms may present from early childhood to
    late adulthood depending on residual enzyme activity.
inheritance:
- name: Autosomal recessive
  inheritance_term:
    preferred_term: Autosomal recessive inheritance
    term:
      id: HP:0000007
      label: Autosomal recessive inheritance
  description: >
    Pompe disease is inherited in an autosomal recessive manner. Affected individuals
    carry biallelic pathogenic variants in the GAA gene. Carrier frequency is estimated
    at approximately 1 in 100-200 in most populations. Disease incidence varies by
    population, estimated at approximately 1 in 40,000 overall.
  evidence:
  - reference: PMID:18929906
    reference_title: "Pompe's disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "It is a pan-ethnic autosomal recessive trait characterised by acid alpha-glucosidase deficiency leading to lysosomal glycogen storage."
    explanation: The Lancet review by van der Ploeg and Reuser establishes Pompe disease as an autosomal recessive trait.
  - reference: ORPHA:365
    reference_title: "Glycogen storage disease due to acid maltase deficiency (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Autosomal recessive"
    explanation: Orphanet records autosomal recessive inheritance for Pompe disease.
prevalence:
- population: Global live births
  percentage: 2.0 per 100,000 live births
  notes: >-
    Recent meta-analysis data suggest a global birth prevalence of 2.0 per
    100,000 live births overall, with infantile-onset disease at 1.0 per
    100,000 and late-onset disease at 2.4 per 100,000. Older evidence reviews
    commonly cited an overall prevalence of about 1 case per 40,000.
  evidence:
  - reference: PMID:39424261
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Global birth prevalence of Pompe disease was 2.0 cases (95% CI: 1.5-2.4) per 100,000 live births. Global birth prevalence of infantile-onset Pompe disease was 1.0 cases (95% CI: 0.5-1.5) per 100,000 live births. Global birth prevalence of late-onset Pompe disease was 2.4 cases (95% CI: 1.8-3.0) per 100,000 live births."
    explanation: This 2024 systematic review and meta-analysis provides pooled global birth prevalence estimates for overall Pompe disease and its major clinical subtypes.
  - reference: PMID:17974725
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The prevalence of Pompe disease has been estimated to be approximately 1 case per 40,000."
    explanation: This evidence synthesis captures the traditional benchmark prevalence estimate used before broader newborn screening data became available.
pathophysiology:
- name: Lysosomal glycogen accumulation
  description: >
    Deficiency of acid alpha-glucosidase (GAA) prevents normal lysosomal degradation
    of glycogen. Glycogen progressively accumulates within lysosomes, establishing
    the substrate-storage lesion that drives downstream autophagic, skeletal muscle,
    respiratory muscle, and cardiac pathology.
  gene:
    preferred_term: GAA
    description: Acid alpha-glucosidase, a lysosomal enzyme that hydrolyzes alpha-1,4 and alpha-1,6 glycosidic linkages in glycogen to release glucose.
    modifier: DECREASED
    term:
      id: hgnc:4065
      label: GAA
  evidence:
  - reference: PMID:32745073
    reference_title: "Pompe disease: pathogenesis, molecular genetics and diagnosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "GAA catalyzes the hydrolysis of α-1,4 and α-1,6-glucosidic bonds of glycogen and its deficiency leads to lysosomal storage of glycogen in several tissues, particularly in muscle."
    explanation: Taverna et al. review confirms that GAA deficiency leads to lysosomal glycogen storage predominantly in muscle tissue.
  - reference: PMID:18929906
    reference_title: "Pompe's disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "acid alpha-glucosidase deficiency leading to lysosomal glycogen storage"
    explanation: The Lancet review establishes the core pathogenic mechanism of GAA deficiency causing lysosomal glycogen accumulation.
  cell_types:
  - preferred_term: Skeletal muscle fiber
    term:
      id: CL:0008002
      label: skeletal muscle fiber
  - preferred_term: Cardiac muscle cell
    term:
      id: CL:0000746
      label: cardiac muscle cell
  biological_processes:
  - preferred_term: Glycogen catabolic process
    term:
      id: GO:0005980
      label: glycogen catabolic process
  - preferred_term: Lysosome organization
    term:
      id: GO:0007040
      label: lysosome organization
  chemical_entities:
  - preferred_term: glycogen
    term:
      id: CHEBI:28087
      label: glycogen
    modifier: INCREASED
  downstream:
  - target: Autophagy dysregulation
    description: Glycogen-overloaded lysosomes perturb lysosome-dependent autophagic flux in muscle.
  - target: Skeletal and respiratory myofiber injury
    description: Glycogen storage in skeletal and respiratory muscles disrupts contractile tissue and respiratory mechanics.
  - target: Cardiomyocyte glycogen storage and hypertrophic remodeling
    description: Glycogen storage in cardiomyocytes drives the hypertrophic cardiac phenotype of infantile-onset disease.
  - target: Hepatomegaly
    description: Lysosomal glycogen storage in infantile-onset disease can involve liver enlargement.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:26889246
      reference_title: "Infantile Pompe disease: A case report and review of the Chinese literature."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "cardiac hypertrophy, hepatomegaly and elevated serum enzyme levels"
      explanation: Infantile Pompe case evidence links the storage phenotype with hepatomegaly.
  - target: Macroglossia
    description: Glycogen storage in tongue musculature contributes to macroglossia in infantile-onset disease.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:39020349
      reference_title: "Enzyme replacement therapy and immunotherapy lead to significant functional improvement in two children with Pompe disease: a case report."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "presented with generalized hypotonia, macroglossia, hyporeflexia, and mild left ventricular hypertrophy"
      explanation: Case evidence documents macroglossia alongside other glycogen-storage manifestations.
  - target: Hearing impairment
    description: The broader lysosomal-storage phenotype includes hearing impairment in a minority of Pompe patients.
    causal_link_type: UNKNOWN
    evidence:
    - reference: ORPHA:365
      reference_title: "Glycogen storage disease due to acid maltase deficiency (Orphanet structured-database record)"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "HP:0000365 | Hearing impairment | Occasional (29-5%)"
      explanation: Orphanet records hearing impairment as an occasional Pompe disease phenotype.
  - target: Thoracic aortic aneurysm
    description: In late-onset disease, systemic glycogen-storage pathology can include adult arteriopathy with ascending thoracic aortic dilatation.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:20301438
      reference_title: "Pompe Disease."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "Some adults have developed arteriopathy, including dilatation of the ascending thoracic aorta."
      explanation: GeneReviews documents adult LOPD arteriopathy with ascending thoracic aortic dilatation.
- name: Autophagy dysregulation
  description: >
    Beyond glycogen accumulation, Pompe disease involves profound dysregulation of
    autophagy. Autophagic buildup in type II muscle fibers represents a major
    pathological feature in both IOPD and LOPD. Impaired autophagosome-lysosome
    fusion leads to accumulation of autophagic debris, which can be as destructive
    to muscle architecture as glycogen storage itself. This autophagic pathology may
    limit the effectiveness of enzyme replacement therapy.
  evidence:
  - reference: PMID:20040311
    reference_title: "Autophagy in skeletal muscle: implications for Pompe disease."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "In the GAA-knockout mouse model, progressive accumulation of autophagic vesicles is restricted to Type II-rich muscle fibers. Not only does this build-up of autophagosomes disrupt the contractile apparatus in the muscle fibers, it also interferes with enzyme replacement therapy by acting as a sink for the recombinant enzyme and preventing its efficient delivery to the lysosomes."
    explanation: Shea and Raben demonstrated in GAA-knockout mice that autophagic buildup disrupts muscle architecture and impairs ERT efficacy by preventing enzyme delivery to lysosomes.
  - reference: PMID:38785980
    reference_title: "Failure of Autophagy in Pompe Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The autophagic pathway is largely responsible for the delivery of cytosolic glycogen to the lysosome where it is degraded to glucose via acid α-glucosidase."
    explanation: Do, Meena, and Raben review links lysosome-dependent autophagy to glycogen delivery and acid alpha-glucosidase-dependent degradation.
  biological_processes:
  - preferred_term: Autophagy
    term:
      id: GO:0006914
      label: autophagy
  cell_types:
  - preferred_term: Skeletal muscle fiber
    term:
      id: CL:0008002
      label: skeletal muscle fiber
  downstream:
  - target: Skeletal and respiratory myofiber injury
    description: Autophagic buildup and impaired lysosomal delivery contribute to progressive muscle fiber damage.
- name: Skeletal and respiratory myofiber injury
  description: >
    Glycogen storage and autophagic debris injure skeletal and respiratory muscle
    fibers, producing progressive limb-girdle weakness, exercise intolerance, and
    respiratory insufficiency.
  evidence:
  - reference: PMID:32745073
    reference_title: "Pompe disease: pathogenesis, molecular genetics and diagnosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "PD is a chronic and progressive pathology usually characterized by limb-girdle muscle weakness and respiratory failure."
    explanation: Directly supports the downstream myofiber-injury phenotype of limb-girdle weakness and respiratory failure.
  - reference: PMID:32505193
    reference_title: "Exercise training alone or in combination with high-protein diet in patients with late onset Pompe disease: results of a cross over study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The GAA deficiency results into glycogen accumulation, especially in fibers of skeletal, respiratory and cardiac muscles; the consequence is a progressive invalidating disease"
    explanation: Supports injury of skeletal and respiratory muscle fibers as a consequence of GAA-deficiency-driven glycogen accumulation.
  cell_types:
  - preferred_term: Skeletal muscle fiber
    term:
      id: CL:0008002
      label: skeletal muscle fiber
  downstream:
  - target: Progressive proximal myopathy
    description: Skeletal muscle fiber injury clinically manifests as progressive proximal and limb-girdle weakness.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:32745073
      reference_title: "Pompe disease: pathogenesis, molecular genetics and diagnosis."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "PD is a chronic and progressive pathology usually characterized by limb-girdle muscle weakness and respiratory failure."
      explanation: Human clinical review links Pompe disease to limb-girdle weakness, supporting the muscle-injury-to-myopathy edge.
  - target: Respiratory insufficiency
    description: Respiratory myofiber injury weakens ventilatory muscles and causes respiratory insufficiency.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:20393176
      reference_title: "A randomized study of alglucosidase alfa in late-onset Pompe's disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Late-onset Pompe's disease is characterized by progressive muscle weakness and loss of respiratory function, leading to early death."
      explanation: Randomized trial background directly links progressive muscle weakness with loss of respiratory function in LOPD.
  - target: Generalized hypotonia
    description: Infantile Pompe myofiber injury manifests as hypotonia and generalized muscle weakness.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:20301438
      reference_title: "Pompe Disease."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "hypotonia, generalized muscle weakness, feeding difficulties, poor growth, and respiratory distress."
      explanation: GeneReviews lists hypotonia and generalized muscle weakness among untreated IOPD features.
  - target: Failure to thrive
    description: Feeding difficulty and poor growth follow from severe infantile muscle and respiratory involvement.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:20301438
      reference_title: "Pompe Disease."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "hypotonia, generalized muscle weakness, feeding difficulties, poor growth, and respiratory distress."
      explanation: GeneReviews links untreated IOPD with feeding difficulties and poor growth.
  - target: Motor delay
    description: Muscle weakness and hypotonia delay acquisition of motor milestones in infantile Pompe disease.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:39020349
      reference_title: "Enzyme replacement therapy and immunotherapy lead to significant functional improvement in two children with Pompe disease: a case report."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Functional tests revealed motor development delay, generalized hypotonia, and positive anti-recombinant human acid alpha-glucosidase IgG antibody titers"
      explanation: Case evidence documents motor delay together with generalized hypotonia.
  - target: Elevated creatine kinase
    description: Ongoing skeletal muscle injury releases creatine kinase into circulation.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:26889246
      reference_title: "Infantile Pompe disease: A case report and review of the Chinese literature."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "creatine kinase level of 1,299"
      explanation: Case evidence documents elevated creatine kinase in infantile Pompe disease.
  - target: Exercise intolerance
    description: Progressive limb-girdle and respiratory myofiber injury limits sustained activity.
    causal_link_type: DIRECT
    evidence:
    - reference: ORPHA:365
      reference_title: "Glycogen storage disease due to acid maltase deficiency (Orphanet structured-database record)"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "HP:0003546 | Exercise intolerance | Frequent (79-30%)"
      explanation: Orphanet records exercise intolerance as a frequent Pompe disease phenotype.
  - target: Fatigue
    description: Progressive skeletal and respiratory muscle involvement contributes to chronic fatigue.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: ORPHA:365
      reference_title: "Glycogen storage disease due to acid maltase deficiency (Orphanet structured-database record)"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "HP:0012378 | Fatigue | Frequent (79-30%)"
      explanation: Orphanet records fatigue as a frequent Pompe disease phenotype.
  - target: Dysphagia
    description: Oropharyngeal and esophageal muscle weakness can impair swallowing.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: ORPHA:365
      reference_title: "Glycogen storage disease due to acid maltase deficiency (Orphanet structured-database record)"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "HP:0002015 | Dysphagia | Occasional (29-5%)"
      explanation: Orphanet records dysphagia as an occasional Pompe disease phenotype.
  - target: Scoliosis
    description: Axial and paraspinal muscle weakness contributes to scoliosis.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:20301438
      reference_title: "Pompe Disease."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "Scoliosis is also frequent."
      explanation: GeneReviews lists scoliosis as a frequent late-onset Pompe manifestation.
  - target: Recurrent respiratory infections
    description: Respiratory muscle weakness and impaired airway clearance predispose to recurrent respiratory infections.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: ORPHA:365
      reference_title: "Glycogen storage disease due to acid maltase deficiency (Orphanet structured-database record)"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "HP:0002205 | Recurrent respiratory infections | Frequent (79-30%)"
      explanation: Orphanet records recurrent respiratory infections as a frequent Pompe disease phenotype.
- name: Cardiomyocyte glycogen storage and hypertrophic remodeling
  description: >
    In infantile-onset Pompe disease, cardiomyocyte glycogen storage produces
    cardiac hypertrophy and hypertrophic cardiomyopathy that contribute to early
    cardiorespiratory morbidity when untreated.
  evidence:
  - reference: PMID:18929906
    reference_title: "Pompe's disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Cardiac hypertrophy is a key feature of classic infantile Pompe's disease."
    explanation: Supports cardiac hypertrophy as a key infantile-onset consequence of Pompe disease.
  - reference: PMID:17151339
    reference_title: "Recombinant human acid [alpha]-glucosidase: major clinical benefits in infantile-onset Pompe disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Infantile-onset Pompe disease is characterized by cardiomyopathy, respiratory and skeletal muscle weakness, and early death."
    explanation: Supports cardiomyopathy as part of the infantile-onset Pompe disease phenotype.
  cell_types:
  - preferred_term: Cardiac muscle cell
    term:
      id: CL:0000746
      label: cardiac muscle cell
  biological_processes:
  - preferred_term: Cardiac muscle hypertrophy
    modifier: INCREASED
    term:
      id: GO:0003300
      label: cardiac muscle hypertrophy
  downstream:
  - target: Hypertrophic cardiomyopathy
    description: Cardiomyocyte glycogen storage and hypertrophic remodeling produce the infantile-onset hypertrophic cardiomyopathy phenotype.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:18929906
      reference_title: "Pompe's disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Cardiac hypertrophy is a key feature of classic infantile Pompe's disease."
      explanation: Human clinical review supports cardiac hypertrophy as the key cardiac manifestation of classic infantile Pompe disease.
  - target: Shortened PR interval
    description: Glycogen deposition in cardiac conduction tissue causes conduction defects with shortened PR interval in infantile-onset Pompe disease.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:20301438
      reference_title: "Pompe Disease."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "Progressive deposition of glycogen results in conduction defects with shortening of the PR interval on EKG."
      explanation: GeneReviews documents shortened PR interval as a conduction manifestation of glycogen deposition.
phenotypes:
- name: Hypertrophic cardiomyopathy
  description: >
    Massive cardiac glycogen storage causes biventricular hypertrophic cardiomyopathy
    in infantile-onset Pompe disease. Left ventricular wall thickness may be
    dramatically increased. This is the hallmark feature distinguishing IOPD from
    LOPD and is a major cause of death if untreated.
  frequency: HP_0040281
  subtype: IOPD
  phenotype_term:
    preferred_term: Hypertrophic cardiomyopathy
    term:
      id: HP:0001639
      label: Hypertrophic cardiomyopathy
  evidence:
  - reference: PMID:18929906
    reference_title: "Pompe's disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Cardiac hypertrophy is a key feature of classic infantile Pompe's disease."
    explanation: The Lancet review confirms cardiac hypertrophy as a key feature of classic infantile Pompe disease.
  - reference: ORPHA:365
    reference_title: "Glycogen storage disease due to acid maltase deficiency (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001639 | Hypertrophic cardiomyopathy | Occasional (29-5%)"
    explanation: Orphanet classifies hypertrophic cardiomyopathy as Occasional across the full Pompe disease spectrum; frequency is higher in IOPD specifically.
  - reference: PMID:17151339
    reference_title: "Recombinant human acid [alpha]-glucosidase: major clinical benefits in infantile-onset Pompe disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Infantile-onset Pompe disease is characterized by cardiomyopathy, respiratory and skeletal muscle weakness, and early death."
    explanation: The Kishnani et al. clinical trial paper confirms cardiomyopathy as a characteristic feature of infantile-onset Pompe disease.
- name: Shortened PR interval
  description: >
    Glycogen deposition in cardiac conduction tissue produces conduction defects
    with shortening of the PR interval on EKG in infantile-onset Pompe disease.
  subtype: IOPD
  phenotype_term:
    preferred_term: Shortened PR interval
    term:
      id: HP:0005165
      label: Shortened PR interval
  evidence:
  - reference: PMID:20301438
    reference_title: "Pompe Disease."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Progressive deposition of glycogen results in conduction defects with shortening of the PR interval on EKG."
    explanation: GeneReviews documents shortened PR interval as a conduction finding in untreated IOPD.
- name: Thoracic aortic aneurysm
  description: >
    Adults with late-onset Pompe disease can develop arteriopathy including
    dilatation of the ascending thoracic aorta, prompting echocardiographic and
    vascular surveillance.
  subtype: LOPD
  phenotype_term:
    preferred_term: Ascending thoracic aortic dilatation
    term:
      id: HP:0012727
      label: Thoracic aortic aneurysm
  evidence:
  - reference: PMID:20301438
    reference_title: "Pompe Disease."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Some adults have developed arteriopathy, including dilatation of the ascending thoracic aorta."
    explanation: GeneReviews documents ascending thoracic aortic dilatation as an adult LOPD vascular complication.
- name: Generalized hypotonia
  description: >
    Severe generalized hypotonia (floppy infant) is a cardinal feature of IOPD.
    Affected infants show profound muscle weakness and poor head control.
    In LOPD, hypotonia may be less severe but progressive.
  frequency: HP_0040281
  subtype: IOPD
  phenotype_term:
    preferred_term: Hypotonia
    term:
      id: HP:0001252
      label: Hypotonia
  evidence:
  - reference: PMID:33554498
    reference_title: "Advances in diagnosis and management of Pompe disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Pompe disease manifests with a broad spectrum of disease severity, ranging from severe infantile-onset diseases such as hypotonia and hypertrophic cardiomyopathy to late-onset diseases such as myopathy and respiratory compromise."
    explanation: Davison review confirms hypotonia as a key manifestation of severe infantile-onset Pompe disease.
  - reference: ORPHA:365
    reference_title: "Glycogen storage disease due to acid maltase deficiency (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0008947 | Floppy infant | Occasional (29-5%)"
    explanation: Orphanet annotates floppy infant as Occasional across the full disease spectrum; frequency is higher in IOPD specifically.
- name: Progressive proximal myopathy
  description: >
    Progressive weakness of proximal and limb-girdle muscles is the predominant
    feature of LOPD. Patients develop difficulty climbing stairs, rising from
    chairs, and walking. The pelvic girdle is typically affected before the
    shoulder girdle.
  frequency: HP_0040281
  subtype: LOPD
  phenotype_term:
    preferred_term: Proximal muscle weakness
    term:
      id: HP:0003701
      label: Proximal muscle weakness
  evidence:
  - reference: PMID:32745073
    reference_title: "Pompe disease: pathogenesis, molecular genetics and diagnosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "PD is a chronic and progressive pathology usually characterized by limb-girdle muscle weakness and respiratory failure."
    explanation: Taverna et al. review confirms that Pompe disease is characterized by progressive limb-girdle muscle weakness.
  - reference: ORPHA:365
    reference_title: "Glycogen storage disease due to acid maltase deficiency (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0009073 | Progressive proximal muscle weakness | Very frequent (99-80%)"
    explanation: Orphanet classifies progressive proximal muscle weakness as Very frequent (99-80%) in Pompe disease.
- name: Respiratory insufficiency
  description: >
    Diaphragmatic and respiratory muscle weakness leads to progressive respiratory
    insufficiency. In LOPD, respiratory failure may be the presenting symptom and
    can precede limb weakness. Many patients eventually require ventilatory
    support. In IOPD, respiratory failure contributes to early death.
  frequency: HP_0040282
  phenotype_term:
    preferred_term: Respiratory insufficiency due to muscle weakness
    term:
      id: HP:0002747
      label: Respiratory insufficiency due to muscle weakness
  evidence:
  - reference: PMID:20393176
    reference_title: "A randomized study of alglucosidase alfa in late-onset Pompe's disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Late-onset Pompe's disease is characterized by progressive muscle weakness and loss of respiratory function, leading to early death."
    explanation: The van der Ploeg et al. NEJM trial confirms progressive loss of respiratory function as characteristic of late-onset Pompe disease.
  - reference: ORPHA:365
    reference_title: "Glycogen storage disease due to acid maltase deficiency (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002747 | Respiratory insufficiency due to muscle weakness | Frequent (79-30%)"
    explanation: Orphanet classifies respiratory insufficiency due to muscle weakness as Frequent (79-30%) in Pompe disease.
- name: Elevated creatine kinase
  description: >
    Serum creatine kinase (CK) levels are typically elevated in Pompe disease,
    reflecting ongoing muscle damage. CK levels are generally 2-15 times the
    upper limit of normal.
  frequency: HP_0040282
  phenotype_term:
    preferred_term: Elevated circulating creatine kinase concentration
    term:
      id: HP:0003236
      label: Elevated circulating creatine kinase concentration
  evidence:
  - reference: PMID:26889246
    reference_title: "Infantile Pompe disease: A case report and review of the Chinese literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "cardiac hypertrophy, hepatomegaly and elevated serum enzyme levels, which was characterized by an aspartate aminotransferase level of 95 U/l, lactate dehydrogenase level of 778 U/l and creatine kinase level of 1,299 U/l"
    explanation: Liu et al. case report documents markedly elevated creatine kinase (1,299 U/l) in an infant with Pompe disease, consistent with ongoing muscle damage.
  - reference: ORPHA:365
    reference_title: "Glycogen storage disease due to acid maltase deficiency (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0003236 | Elevated circulating creatine kinase concentration | Frequent (79-30%)"
    explanation: Orphanet classifies elevated CK as Frequent (79-30%) in Pompe disease.
- name: Hepatomegaly
  description: >
    Liver enlargement due to glycogen accumulation is common in IOPD but
    uncommon in LOPD.
  frequency: HP_0040282
  subtype: IOPD
  phenotype_term:
    preferred_term: Hepatomegaly
    term:
      id: HP:0002240
      label: Hepatomegaly
  evidence:
  - reference: PMID:26889246
    reference_title: "Infantile Pompe disease: A case report and review of the Chinese literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "a newborn who was found to have cardiac hypertrophy, hepatomegaly and elevated serum enzyme levels"
    explanation: Liu et al. case report documents hepatomegaly as a presenting feature of infantile Pompe disease.
  - reference: ORPHA:365
    reference_title: "Glycogen storage disease due to acid maltase deficiency (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002240 | Hepatomegaly | Frequent (79-30%)"
    explanation: Orphanet classifies hepatomegaly as Frequent (79-30%) in Pompe disease.
- name: Macroglossia
  description: >
    Enlargement of the tongue is a characteristic feature of IOPD, caused by
    glycogen accumulation in the tongue musculature.
  frequency: HP_0040283
  subtype: IOPD
  phenotype_term:
    preferred_term: Macroglossia
    term:
      id: HP:0000158
      label: Macroglossia
  evidence:
  - reference: PMID:39020349
    reference_title: "Enzyme replacement therapy and immunotherapy lead to significant functional improvement in two children with Pompe disease: a case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "presented with generalized hypotonia, macroglossia, hyporeflexia, and mild left ventricular hypertrophy"
    explanation: Castellar-Leones et al. case report documents macroglossia as a presenting feature in an infant with early-onset Pompe disease.
  - reference: ORPHA:365
    reference_title: "Glycogen storage disease due to acid maltase deficiency (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000158 | Macroglossia | Occasional (29-5%)"
    explanation: Orphanet classifies macroglossia as Occasional (29-5%) across the full Pompe disease spectrum.
- name: Failure to thrive
  description: >
    Poor weight gain and growth failure in IOPD due to feeding difficulties
    and systemic energy deficit from impaired glycogen metabolism.
  frequency: HP_0040282
  subtype: IOPD
  phenotype_term:
    preferred_term: Failure to thrive
    term:
      id: HP:0001508
      label: Failure to thrive
  evidence:
  - reference: PMID:16737883
    reference_title: "A retrospective, multinational, multicenter study on the natural history of infantile-onset Pompe disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "feeding difficulties (57%), and failure to thrive (53%) appeared after a median age of approximately 4.0 months"
    explanation: Kishnani et al. natural history study of 168 IOPD patients found failure to thrive in 53% of cases.
  - reference: ORPHA:365
    reference_title: "Glycogen storage disease due to acid maltase deficiency (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001508 | Failure to thrive | Frequent (79-30%)"
    explanation: Orphanet classifies failure to thrive as Frequent (79-30%) in Pompe disease.
- name: Motor delay
  description: >
    Delayed motor milestones in IOPD; infants often never achieve independent
    sitting or walking without treatment. In LOPD, motor decline may manifest
    as loss of previously acquired motor skills.
  frequency: HP_0040282
  subtype: IOPD
  phenotype_term:
    preferred_term: Motor delay
    term:
      id: HP:0001270
      label: Motor delay
  evidence:
  - reference: PMID:39020349
    reference_title: "Enzyme replacement therapy and immunotherapy lead to significant functional improvement in two children with Pompe disease: a case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Functional tests revealed motor development delay, generalized hypotonia, and positive anti-recombinant human acid alpha-glucosidase IgG antibody titers"
    explanation: Castellar-Leones et al. case report documents motor development delay as a feature of early-onset Pompe disease.
  - reference: ORPHA:365
    reference_title: "Glycogen storage disease due to acid maltase deficiency (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001270 | Motor delay | Frequent (79-30%)"
    explanation: Orphanet classifies motor delay as Frequent (79-30%) in Pompe disease.
- name: Exercise intolerance
  description: >
    Reduced ability to sustain physical activity is a common feature of Pompe
    disease, particularly in LOPD, reflecting progressive skeletal muscle
    glycogen accumulation and energy metabolism impairment.
  frequency: HP_0040282
  phenotype_term:
    preferred_term: Exercise intolerance
    term:
      id: HP:0003546
      label: Exercise intolerance
  evidence:
  - reference: ORPHA:365
    reference_title: "Glycogen storage disease due to acid maltase deficiency (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0003546 | Exercise intolerance | Frequent (79-30%)"
    explanation: Orphanet classifies exercise intolerance as Frequent (79-30%) in Pompe disease.
- name: Fatigue
  description: >
    Chronic fatigue is a commonly reported symptom in Pompe disease,
    affecting quality of life in both IOPD and LOPD patients.
  frequency: HP_0040282
  phenotype_term:
    preferred_term: Fatigue
    term:
      id: HP:0012378
      label: Fatigue
  evidence:
  - reference: ORPHA:365
    reference_title: "Glycogen storage disease due to acid maltase deficiency (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0012378 | Fatigue | Frequent (79-30%)"
    explanation: Orphanet classifies fatigue as Frequent (79-30%) in Pompe disease.
- name: Dysphagia
  description: >
    Swallowing difficulties may occur in Pompe disease due to weakness of
    oropharyngeal and esophageal musculature.
  frequency: HP_0040283
  phenotype_term:
    preferred_term: Dysphagia
    term:
      id: HP:0002015
      label: Dysphagia
  evidence:
  - reference: ORPHA:365
    reference_title: "Glycogen storage disease due to acid maltase deficiency (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002015 | Dysphagia | Occasional (29-5%)"
    explanation: Orphanet classifies dysphagia as Occasional (29-5%) in Pompe disease.
- name: Scoliosis
  description: >
    Spinal deformity secondary to paraspinal muscle weakness, occurring
    particularly in patients with progressive proximal myopathy.
  frequency: HP_0040283
  phenotype_term:
    preferred_term: Scoliosis
    term:
      id: HP:0002650
      label: Scoliosis
  evidence:
  - reference: ORPHA:365
    reference_title: "Glycogen storage disease due to acid maltase deficiency (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002650 | Scoliosis | Occasional (29-5%)"
    explanation: Orphanet classifies scoliosis as Occasional (29-5%) in Pompe disease.
- name: Hearing impairment
  description: >
    Sensorineural hearing loss has been reported in Pompe disease,
    likely related to glycogen accumulation in the inner ear structures.
  frequency: HP_0040283
  phenotype_term:
    preferred_term: Hearing impairment
    term:
      id: HP:0000365
      label: Hearing impairment
  evidence:
  - reference: ORPHA:365
    reference_title: "Glycogen storage disease due to acid maltase deficiency (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000365 | Hearing impairment | Occasional (29-5%)"
    explanation: Orphanet classifies hearing impairment as Occasional (29-5%) in Pompe disease.
- name: Recurrent respiratory infections
  description: >
    Recurrent respiratory infections are a frequent complication of Pompe
    disease, resulting from respiratory muscle weakness and impaired
    airway clearance.
  frequency: HP_0040282
  phenotype_term:
    preferred_term: Recurrent respiratory infections
    term:
      id: HP:0002205
      label: Recurrent respiratory infections
  evidence:
  - reference: ORPHA:365
    reference_title: "Glycogen storage disease due to acid maltase deficiency (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002205 | Recurrent respiratory infections | Frequent (79-30%)"
    explanation: Orphanet classifies recurrent respiratory infections as Frequent (79-30%) in Pompe disease.
histopathology:
- name: Glycogen accumulation in muscle fiber lysosomes
  description: >
    Muscle pathology in Pompe disease includes lysosomal glycogen accumulation
    within muscle fibers, corresponding to the storage lesion caused by deficient
    lysosomal acid alpha-glucosidase activity.
  frequency: FREQUENT
  diagnostic: true
  evidence:
  - reference: ORPHA:365
    reference_title: "Glycogen storage disease due to acid maltase deficiency (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0030231 | Glycogen accumulation in muscle fiber lysosomes | Frequent (79-30%)"
    explanation: Orphanet records glycogen accumulation in muscle fiber lysosomes as a frequent Pompe disease finding.
genetic:
- name: GAA gene mutations
  gene_term:
    preferred_term: GAA
    term:
      id: hgnc:4065
      label: GAA
  association: Causative
  notes: >
    Over 600 pathogenic variants in the GAA gene have been identified. The most
    common variant in Caucasian populations is the intronic splice-site mutation
    c.-32-13T>G (IVS1), which retains some residual enzyme activity and is
    typically associated with LOPD. Null mutations that abolish all enzyme activity
    are associated with severe IOPD. Genotype-phenotype correlations are complex,
    with residual enzyme activity being the primary determinant of disease severity.
  evidence:
  - reference: PMID:32745073
    reference_title: "Pompe disease: pathogenesis, molecular genetics and diagnosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Currently, more than 560 mutations spread throughout GAA gene have been reported."
    explanation: Taverna et al. review confirms the large number of pathogenic variants reported in the GAA gene.
  - reference: CGGV:assertion_0554320e-6a8f-4c39-be7f-99959a8341ee-2019-01-23T170000.000Z
    reference_title: "GAA / glycogen storage disease II (Definitive)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "GAA | HGNC:4065 | glycogen storage disease II | MONDO:0009290 | AR | Definitive"
    explanation: ClinGen classifies the GAA-glycogen storage disease II gene-disease relationship as definitive with autosomal recessive inheritance.
  variants:
  - name: c.-32-13T>G (IVS1)
    description: >
      The most common GAA pathogenic variant in Caucasian populations. This
      intronic variant affects splicing efficiency, allowing some normal transcript
      production and residual enzyme activity. Typically associated with late-onset
      disease when compound heterozygous with another pathogenic variant.
biochemical:
- name: Decreased acid alpha-glucosidase activity
  presence: DECREASED
  context: >
    Deficient lysosomal acid alpha-glucosidase activity is the defining biochemical
    abnormality and can be assayed in dried blood spot or liquid blood samples.
  readouts:
  - target: Lysosomal glycogen accumulation
    relationship: READOUT_OF
    direction: NEGATIVE
    endpoint_context: DIAGNOSTIC
    interpretation: Decreased acid alpha-glucosidase activity reports the upstream enzymatic defect that permits lysosomal glycogen storage.
    evidence:
    - reference: PMID:33554498
      reference_title: "Advances in diagnosis and management of Pompe disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The diagnosis requires demonstration of deficiency of the lysosomal acid alpha-glucosidase enzyme"
      explanation: Diagnostic review evidence identifies decreased GAA activity as the defining biochemical abnormality.
  evidence:
  - reference: PMID:33554498
    reference_title: "Advances in diagnosis and management of Pompe disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The diagnosis requires demonstration of deficiency of the lysosomal acid alpha-glucosidase enzyme, which can be assayed in dried blood spot or liquid blood samples, together with supportive biomarker tests, and confirmed with molecular genetic analysis."
    explanation: Directly supports decreased acid alpha-glucosidase activity as the diagnostic biochemical abnormality and names relevant assay sample types.
  - reference: ORPHA:365
    reference_title: "Glycogen storage disease due to acid maltase deficiency (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0034932 | Decreased circulating acid maltase activity | Very frequent (99-80%)"
    explanation: Orphanet records decreased circulating acid maltase activity as very frequent in Pompe disease.
- name: Urine total glucotetrasaccharide (Hex4)
  presence: INCREASED
  context: >
    Urinary total glucotetrasaccharide (Hex4/Glc4) is a glycogen-derived biochemical
    biomarker used as an adjunct for Pompe disease diagnosis and longitudinal
    monitoring.
  readouts:
  - target: Lysosomal glycogen accumulation
    relationship: READOUT_OF
    direction: POSITIVE
    endpoint_context: DIAGNOSTIC
    interpretation: Elevated urinary Glc4 reports increased glycogen turnover from lysosomal glycogen storage.
    evidence:
    - reference: PMID:11078593
      reference_title: "Liquid chromatographic assay for a glucose tetrasaccharide, a putative biomarker for the diagnosis of Pompe disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "all the patients had elevated Glc(4) levels compared with age-matched controls."
      explanation: Biomarker study demonstrates elevated Glc4 in enzymatically confirmed Pompe disease patients.
  evidence:
  - reference: PMID:11078593
    reference_title: "Liquid chromatographic assay for a glucose tetrasaccharide, a putative biomarker for the diagnosis of Pompe disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "all the patients had elevated Glc(4) levels compared with age-matched controls."
    explanation: Supports increased urine/plasma Glc4 as a Pompe disease biomarker.
  - reference: PMID:20301438
    reference_title: "Pompe Disease."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "CK level, and urine total glucotetrasaccharide (Hex4) level."
    explanation: GeneReviews includes urine total Hex4 in Pompe disease surveillance.
treatments:
- name: Enzyme replacement therapy (ERT)
  description: >
    Intravenous infusion of recombinant human GAA is the standard of care for
    Pompe disease. Alglucosidase alfa (Myozyme/Lumizyme) was the first approved
    ERT (2006). Avalglucosidase alfa (Nexviazyme), a next-generation ERT with
    enhanced mannose-6-phosphate receptor binding, was approved in 2021 and
    shows improved skeletal muscle uptake. ERT significantly improves survival
    and cardiac outcomes in IOPD and stabilizes or improves respiratory and
    motor function in LOPD.
  treatment_term:
    preferred_term: enzyme replacement or supplementation therapy
    term:
      id: MAXO:0000933
      label: enzyme replacement or supplementation therapy
  target_phenotypes:
  - preferred_term: Hypertrophic cardiomyopathy
    term:
      id: HP:0001639
      label: Hypertrophic cardiomyopathy
  - preferred_term: Proximal muscle weakness
    term:
      id: HP:0003701
      label: Proximal muscle weakness
  - preferred_term: Respiratory insufficiency due to muscle weakness
    term:
      id: HP:0002747
      label: Respiratory insufficiency due to muscle weakness
  target_mechanisms:
  - target: Lysosomal glycogen accumulation
    treatment_effect: MODULATES
    description: Recombinant human GAA supplies the deficient lysosomal enzyme upstream of glycogen storage.
    evidence:
    - reference: PMID:17151339
      reference_title: "Recombinant human acid [alpha]-glucosidase: major clinical benefits in infantile-onset Pompe disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Recombinant human acid alpha-glucosidase is safe and effective for treatment of infantile-onset Pompe disease."
      explanation: Clinical trial evidence supports rhGAA as enzyme replacement therapy for the upstream GAA deficiency.
  evidence:
  - reference: PMID:17151339
    reference_title: "Recombinant human acid [alpha]-glucosidase: major clinical benefits in infantile-onset Pompe disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All patients (100%) survived to 18 months of age. A Cox proportional hazards analysis demonstrated that treatment reduced the risk of death by 99%, reduced the risk of death or invasive ventilation by 92%, and reduced the risk of death or any type of ventilation by 88%, as compared to an untreated historical control group."
    explanation: The landmark Kishnani et al. clinical trial demonstrated that rhGAA ERT reduced risk of death by 99% in infantile-onset Pompe disease compared to untreated historical controls.
  - reference: PMID:20393176
    reference_title: "A randomized study of alglucosidase alfa in late-onset Pompe's disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "At 78 weeks, the estimated mean changes from baseline in the primary end points favored alglucosidase alfa (an increase of 28.1+/-13.1 m on the 6-minute walk test and an absolute increase of 3.4+/-1.2 percentage points in FVC; P=0.03 and P=0.006, respectively)."
    explanation: The van der Ploeg et al. NEJM randomized controlled trial showed that alglucosidase alfa significantly improved walking distance and stabilized pulmonary function in late-onset Pompe disease.
  - reference: PMID:34800399
    reference_title: "Safety and efficacy of avalglucosidase alfa versus alglucosidase alfa in patients with late-onset Pompe disease (COMET): a phase 3, randomised, multicentre trial."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We consider that this study provides evidence of clinically meaningful improvement with avalglucosidase alfa therapy over alglucosidase alfa in respiratory function, ambulation, and functional endurance, with no new safety signals reported."
    explanation: The COMET phase 3 trial demonstrated that avalglucosidase alfa provided clinically meaningful improvements in respiratory function over alglucosidase alfa in late-onset Pompe disease.
- name: Cipaglucosidase alfa plus miglustat
  description: >
    A two-component therapy combining cipaglucosidase alfa, a novel recombinant
    human acid alpha-glucosidase, with miglustat, an enzyme stabilizer that
    enhances intracellular delivery. FDA-approved in 2023 for adults with
    late-onset Pompe disease. The PROPEL phase 3 trial (125 patients) showed
    numerical improvements in 6-minute walk distance and respiratory function
    versus alglucosidase alfa, with benefits particularly in patients previously
    receiving ERT for more than 2 years.
  treatment_term:
    preferred_term: Enzyme replacement therapy with enzyme stabilizer
    term:
      id: MAXO:0000058
      label: pharmacotherapy
    therapeutic_agent:
    - preferred_term: cipaglucosidase alfa
      term:
        id: NCIT:C175059
        label: Cipaglucosidase Alfa
    - preferred_term: miglustat
      term:
        id: CHEBI:50381
        label: miglustat
  target_phenotypes:
  - preferred_term: Proximal muscle weakness
    term:
      id: HP:0003701
      label: Proximal muscle weakness
  - preferred_term: Respiratory insufficiency due to muscle weakness
    term:
      id: HP:0002747
      label: Respiratory insufficiency due to muscle weakness
  evidence:
  - reference: PMID:34800400
    reference_title: "Safety and efficacy of cipaglucosidase alfa plus miglustat versus alglucosidase alfa plus placebo in late-onset Pompe disease (PROPEL): an international, randomised, double-blind, parallel-group, phase 3 trial."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "At week 52, mean change from baseline in 6-min walk distance was 20·8 m (SE 4·6) in the cipaglucosidase alfa plus miglustat group versus 7·2 m (6·6) in the alglucosidase alfa plus placebo group using last observation carried forward (between-group difference 13·6 m [95% CI -2·8 to 29·9])."
    explanation: The PROPEL phase 3 trial showed a numerical improvement in 6-minute walk distance with cipaglucosidase alfa plus miglustat versus standard ERT, though the primary endpoint did not reach statistical superiority in the overall population.
- name: Respiratory support
  description: >
    Non-invasive ventilation (BiPAP) or invasive mechanical ventilation may be
    required for respiratory insufficiency. Many LOPD patients require nocturnal
    ventilatory support, and some progress to continuous ventilator dependence.
  treatment_term:
    preferred_term: artificial respiration
    term:
      id: MAXO:0000503
      label: artificial respiration
  target_phenotypes:
  - preferred_term: Respiratory insufficiency due to muscle weakness
    term:
      id: HP:0002747
      label: Respiratory insufficiency due to muscle weakness
  evidence:
  - reference: PMID:22173792
    reference_title: "Consensus treatment recommendations for late-onset Pompe disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A multidisciplinary team should be involved to properly treat the pulmonary, neuromuscular, orthopedic, and gastrointestinal elements of late-onset Pompe disease."
    explanation: Consensus treatment recommendations support pulmonary management as a component of Pompe disease care.
  - reference: PMID:39457174
    reference_title: "Effectiveness of Respiratory Muscle Training in Pompe Disease: A Systematic Review and Meta-Analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "RMT has potential to be integrated into the cardioplulmonary rehabilitation for patients with Pompe disease."
    explanation: Supports respiratory muscle training as part of cardiopulmonary rehabilitation in Pompe disease.
- name: Cardiac medication and anesthesia precautions
  description: >
    Cardiac medication and anesthesia planning require Pompe-specific caution.
    GeneReviews warns that digoxin, inotropes, diuretics, and afterload-reducing
    agents may worsen left ventricular outflow obstruction in some stages, and
    that anesthesia should be used only when necessary because cardiovascular and
    respiratory reserve may be limited.
  treatment_term:
    preferred_term: supportive care
    term:
      id: MAXO:0000950
      label: supportive care
  target_phenotypes:
  - preferred_term: Hypertrophic cardiomyopathy
    term:
      id: HP:0001639
      label: Hypertrophic cardiomyopathy
  - preferred_term: Respiratory insufficiency due to muscle weakness
    term:
      id: HP:0002747
      label: Respiratory insufficiency due to muscle weakness
  evidence:
  - reference: PMID:20301438
    reference_title: "Pompe Disease."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "The use of digoxin, ionotropes, diuretics, and afterload-reducing agents may worsen left ventricular outflow obstruction"
    explanation: GeneReviews lists cardiac drugs that may worsen left ventricular outflow obstruction.
  - reference: PMID:20301438
    reference_title: "Pompe Disease."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Anesthesia should be used only when absolutely necessary because reduced cardiovascular return and underlying respiratory insufficiency pose significant risks."
    explanation: GeneReviews documents anesthesia risk from combined cardiovascular and respiratory vulnerability.
- name: Physical therapy and rehabilitation
  description: >
    Structured physical therapy and rehabilitation programs help maintain
    mobility, prevent contractures, and optimize residual muscle function.
    Exercise programs should be tailored to avoid overexertion.
  treatment_term:
    preferred_term: Physical therapy
    term:
      id: MAXO:0000011
      label: physical therapy
  target_phenotypes:
  - preferred_term: Proximal muscle weakness
    term:
      id: HP:0003701
      label: Proximal muscle weakness
  - preferred_term: Exercise intolerance
    term:
      id: HP:0003546
      label: Exercise intolerance
  evidence:
  - reference: PMID:31811531
    reference_title: "Adapted physical activity and therapeutic exercise in late-onset Pompe disease (LOPD): a two-step rehabilitative approach."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Therefore, we evaluated the role of physical activity, therapeutic exercise, and pulmonary rehabilitation programs in order to promote an appropriate management of motor and respiratory dysfunctions and improve QoL in patients with LOPD."
    explanation: Supports therapeutic exercise and rehabilitation programs for motor and respiratory dysfunction in late-onset Pompe disease.
- name: Dietary management
  description: >
    High-protein diet may help preserve muscle mass. In IOPD, specialized
    feeding support including nasogastric or gastrostomy feeding may be needed.
  treatment_term:
    preferred_term: Dietary management
    term:
      id: MAXO:0000088
      label: dietary intervention
  target_phenotypes:
  - preferred_term: Proximal muscle weakness
    term:
      id: HP:0003701
      label: Proximal muscle weakness
  - preferred_term: Exercise intolerance
    term:
      id: HP:0003546
      label: Exercise intolerance
  target_mechanisms:
  - target: Skeletal and respiratory myofiber injury
    treatment_effect: MODULATES
    description: High-protein diet combined with exercise is intended to support residual muscle function in late-onset Pompe disease.
    evidence:
    - reference: PMID:32505193
      reference_title: "Exercise training alone or in combination with high-protein diet in patients with late onset Pompe disease: results of a cross over study."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Exercise training, particularly if combined with high-protein diet, could reverse this decrease and result in an improvement, which was accompanied by improved quality of life."
      explanation: Clinical study supports diet-plus-exercise as a modifier of muscle function and quality of life.
  evidence:
  - reference: PMID:32505193
    reference_title: "Exercise training alone or in combination with high-protein diet in patients with late onset Pompe disease: results of a cross over study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Exercise training, particularly if combined with high-protein diet, could reverse this decrease and result in an improvement, which was accompanied by improved quality of life."
    explanation: Supports high-protein dietary intervention in combination with exercise for late-onset Pompe disease.
- name: Genetic counseling
  description: >
    Genetic counseling for families with Pompe disease addresses autosomal
    recessive recurrence risk, carrier testing for relatives, and prenatal or
    preimplantation genetic testing once familial GAA variants are known.
  treatment_term:
    preferred_term: genetic counseling
    term:
      id: MAXO:0000079
      label: genetic counseling
  target_mechanisms:
  - target: GAA gene mutations
    treatment_effect: MODULATES
    description: Counseling and reproductive testing are anchored to the family's causal GAA pathogenic variants.
    evidence:
    - reference: PMID:20301438
      reference_title: "Pompe Disease."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "molecular genetic carrier testing for at-risk relatives and prenatal/preimplantation genetic testing are possible."
      explanation: GeneReviews supports carrier and prenatal/preimplantation testing once familial GAA variants are known.
  evidence:
  - reference: PMID:20301438
    reference_title: "Pompe Disease."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Pompe disease is inherited in an autosomal recessive manner."
    explanation: GeneReviews establishes the inheritance basis for Pompe disease genetic counseling.
notes: >
  Pompe disease was first described by J.C. Pompe in 1932. The concept of
  lysosomal storage was established by Hers in 1963. Enzyme replacement therapy
  with alglucosidase alfa was approved in 2006. Newborn screening programs have
  enabled earlier diagnosis and treatment of IOPD, significantly improving
  outcomes.
  The development of CRIM (cross-reactive immunologic material) status assessment
  is important for predicting immune response to ERT - CRIM-negative patients
  (who produce no endogenous GAA protein) are at high risk for developing
  high-sustained antibody titers that can render ERT ineffective. Gene therapy
  approaches are in clinical trials. Long-term survivors with Pompe disease are
  now manifesting novel aspects including widespread vascular disease, smooth
  muscle and central nervous system involvement.
references:
- reference: PMID:20301438
  title: "Pompe Disease."
  tags:
  - GeneReviews
- reference: PMID:18929906
  title: "Pompe's disease."
- reference: PMID:11078593
  title: "Liquid chromatographic assay for a glucose tetrasaccharide, a putative biomarker for the diagnosis of Pompe disease."
- reference: PMID:32745073
  title: "Pompe disease: pathogenesis, molecular genetics and diagnosis."
- reference: PMID:17151339
  title: "Recombinant human acid [alpha]-glucosidase: major clinical benefits in infantile-onset Pompe disease."
- reference: PMID:20393176
  title: "A randomized study of alglucosidase alfa in late-onset Pompe's disease."
- reference: PMID:34800399
  title: "Safety and efficacy of avalglucosidase alfa versus alglucosidase alfa in patients with late-onset Pompe disease (COMET): a phase 3, randomised, multicentre trial."
- reference: PMID:37036722
  title: "Efficacy and Safety of Avalglucosidase Alfa in Patients With Late-Onset Pompe Disease After 97 Weeks: A Phase 3 Randomized Clinical Trial."
- reference: PMID:20040311
  title: "Autophagy in skeletal muscle: implications for Pompe disease."
- reference: PMID:38785980
  title: "Failure of Autophagy in Pompe Disease."
- reference: PMID:33554498
  title: "Advances in diagnosis and management of Pompe disease."
- reference: PMID:16737883
  title: "A retrospective, multinational, multicenter study on the natural history of infantile-onset Pompe disease."
- reference: PMID:26889246
  title: "Infantile Pompe disease: A case report and review of the Chinese literature."
- reference: PMID:39020349
  title: "Enzyme replacement therapy and immunotherapy lead to significant functional improvement in two children with Pompe disease: a case report."
- reference: PMID:24715333
  title: "Enzyme therapy and immune response in relation to CRIM status: the Dutch experience in classic infantile Pompe disease."
- reference: PMID:34800400
  title: "Safety and efficacy of cipaglucosidase alfa plus miglustat versus alglucosidase alfa plus placebo in late-onset Pompe disease (PROPEL): an international, randomised, double-blind, parallel-group, phase 3 trial."
- reference: PMID:22173792
  title: "Consensus treatment recommendations for late-onset Pompe disease."
- reference: PMID:31811531
  title: "Adapted physical activity and therapeutic exercise in late-onset Pompe disease (LOPD): a two-step rehabilitative approach."
- reference: PMID:32505193
  title: "Exercise training alone or in combination with high-protein diet in patients with late onset Pompe disease: results of a cross over study."
- reference: PMID:39457174
  title: "Effectiveness of Respiratory Muscle Training in Pompe Disease: A Systematic Review and Meta-Analysis."
- reference: ORPHA:365
  title: "Glycogen storage disease due to acid maltase deficiency"

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