Overview
Glycogen storage disease due to acid maltase deficiency, adult onset, is also known as late-onset Pompe disease or adult-onset glycogen storage disease type II (GSD II). This condition is caused by a deficiency of the enzyme acid alpha-glucosidase (also called acid maltase), which is responsible for breaking down glycogen inside lysosomes — small compartments within cells. When this enzyme does not work properly, glycogen builds up in cells, especially in muscle tissue, leading to progressive muscle damage. In the adult-onset form, symptoms typically begin in the teenage years or adulthood, though the exact age can vary. The most common problems include progressive weakness of the muscles in the hips, thighs, and trunk (proximal muscles), difficulty breathing (especially when lying down), and fatigue. Over time, breathing problems can become severe and may require ventilatory support. Unlike the infantile form of Pompe disease, the heart is usually not significantly affected in adults. The treatment landscape has improved significantly since the approval of enzyme replacement therapy (ERT). This therapy provides the missing enzyme through regular intravenous infusions and can help slow disease progression. Physical therapy, respiratory support, and regular monitoring are also important parts of care. Note that this Orphanet entry is marked as 'OBSOLETE,' meaning it has been merged into the broader classification of late-onset Pompe disease (LOPD). Patients searching for this condition should look under Pompe disease or glycogen storage disease type II for the most current information.
Also known as:
Key symptoms:
Progressive weakness in the legs and hipsDifficulty climbing stairsTrouble getting up from a chair or the floorShortness of breath, especially when lying flatFatigue and reduced staminaLower back painDifficulty walking or waddling gaitMorning headaches from nighttime breathing problemsSleep apnea or disrupted sleepDifficulty with exercise or physical activityWeak trunk and core musclesBreathing problems that worsen over timeMuscle cramps
Autosomal recessive
Passed on when both parents carry the same gene change; often skips generations
Adult
Begins in adulthood (age 18 or older)
Treatments
No FDA-approved treatments are currently listed for OBSOLETE: Glycogen storage disease due to acid maltase deficiency, adult onset.
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Specialists
View all specialists →No specialists are currently listed for OBSOLETE: Glycogen storage disease due to acid maltase deficiency, adult onset.
Treatment Centers
8 centersBaylor College of Medicine Rare Disease Center ↗
Baylor College of Medicine
📍 Houston, TX
🏥 NORDStanford Medicine Rare Disease Center ↗
Stanford Medicine
📍 Stanford, CA
🔬 UDNNIH Clinical Center Undiagnosed Diseases Program ↗
National Institutes of Health
📍 Bethesda, MD
🔬 UDNUCLA UDN Clinical Site ↗
UCLA Health
📍 Los Angeles, CA
🔬 UDNBaylor College of Medicine UDN Clinical Site ↗
Baylor College of Medicine
📍 Houston, TX
🔬 UDNHarvard/MGH UDN Clinical Site ↗
Massachusetts General Hospital
📍 Boston, MA
🏥 NORDMayo Clinic Center for Individualized Medicine ↗
Mayo Clinic
📍 Rochester, MN
👤 Mayo Clinic Center for Individualized Medicine
🏥 NORDUCLA Rare Disease Day Program ↗
UCLA Health
📍 Los Angeles, CA
Travel Grants
No travel grants are currently matched to OBSOLETE: Glycogen storage disease due to acid maltase deficiency, adult onset.
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Caregiver Resources
NORD Caregiver Resources
Support, advocacy, and financial assistance for caregivers of rare disease patients.
Mental Health Support
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Family & Caregiver Grants
Financial assistance programs specifically for caregivers of rare disease patients.
Social Security Disability
Learn how rare disease patients may qualify for SSDI/SSI benefits.
Questions for your doctor
Bring these to your next appointment
- Q1.What is my current level of muscle and breathing function, and how will you track changes over time?,Should I start enzyme replacement therapy now, and which ERT option is best for me?,What kind of physical activity is safe and beneficial for me?,Do I need a sleep study or nighttime breathing support?,Should my family members be tested for this condition?,Are there any clinical trials I might be eligible for?,What emergency signs should I watch for, and what should I do if my breathing suddenly worsens?
Common questions about OBSOLETE: Glycogen storage disease due to acid maltase deficiency, adult onset
What is OBSOLETE: Glycogen storage disease due to acid maltase deficiency, adult onset?
Glycogen storage disease due to acid maltase deficiency, adult onset, is also known as late-onset Pompe disease or adult-onset glycogen storage disease type II (GSD II). This condition is caused by a deficiency of the enzyme acid alpha-glucosidase (also called acid maltase), which is responsible for breaking down glycogen inside lysosomes — small compartments within cells. When this enzyme does not work properly, glycogen builds up in cells, especially in muscle tissue, leading to progressive muscle damage. In the adult-onset form, symptoms typically begin in the teenage years or adulthood, t
How is OBSOLETE: Glycogen storage disease due to acid maltase deficiency, adult onset inherited?
OBSOLETE: Glycogen storage disease due to acid maltase deficiency, adult onset follows a autosomal recessive inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does OBSOLETE: Glycogen storage disease due to acid maltase deficiency, adult onset typically begin?
Typical onset of OBSOLETE: Glycogen storage disease due to acid maltase deficiency, adult onset is adult. Age of onset can vary across affected individuals.