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Start free with EleplanGlycogen storage disease due to acid maltase deficiency
ORPHA:365Disease
Also called Alpha-1,4-glucosidase acid deficiency · GSD due to acid maltase deficiency · GSD type 2 · GSD type II · Glycogen storage disease type 2 · Glycogen storage disease type II · Glycogenosis due to acid maltase deficiency · Glycogenosis type 2 · Glycogenosis type II · Pompe disease
What it is
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.
Key facts
- Prevalence
- 1-9 / 100 000 (Europe)
- Age of onset
- Adolescent, Adult, Antenatal, Childhood, Infancy, Neonatal
- Inheritance
- Autosomal recessive
- Classified as
- Disease
Prevalence figures describe populations, not individuals, and are often estimates from a single study. Where the figure is an incidence or a birth prevalence, it says so.
Signs and symptoms
Very common80–99%
4Common30–79%
31- Areflexia
- Camptocormia
- Cardiomegaly
- Delayed speech and language development
- Difficulty climbing stairs
- Elevated circulating alanine aminotransferase concentration
- Elevated circulating creatine kinase concentration
- EMG: myopathic abnormalities
- Exercise intolerance
- Exertional dyspnea
- Failure to thrive
- Fatigue
- Feeding difficulties in infancy
- Gait disturbance
- Glycogen accumulation in muscle fiber lysosomes
- Gowers sign
- Growth delay
- Heart murmur
- Hepatomegaly
- Hypomimic face
- Hyporeflexia
- Increased circulating lactate dehydrogenase concentration
- Left ventricular hypertrophy
- Lower limb muscle weakness
- Motor delay
- Myalgia
- Recurrent respiratory infections
- Respiratory insufficiency
- Respiratory insufficiency due to muscle weakness
- Respiratory tract infection
- Tongue fasciculations
These ranges are how often a sign appears across everyone diagnosed, not a prediction for one person — most people have some of these and not others. Orphanet also records findings that are specifically absent in this disease; those are in the data but not listed here.
Genes reported in subtypes
Orphanet records this gene on 2 more specific entries under this disorder, not on this entry itself:
A well-studied disease is usually split into subtypes, and the gene is curated on whichever one the evidence belongs to. Open a subtype to see which gene goes with it.
ICD-10 codes
ICD-10 has no distinct code for most rare diseases, so many are filed under the nearest available one. A shared code identifies the group, not this disease — the ORPHAcode above is what identifies it.
Related health topics
Reached through the ICD-10 categories this disease is filed under, so these describe the broader group rather than this disease specifically.
Cross-references
Orphadata Science: Free access data from Orphanet. © INSERM 1999. Data version 2026-06-23. Available under CC BY 4.0. This is a reference, not medical advice.
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