Overview
Methylmalonic acidemia due to methylmalonyl-CoA epimerase deficiency is an extremely rare inherited metabolic disorder. It is sometimes called methylmalonyl-CoA racemase deficiency. In this condition, the body has trouble breaking down certain proteins and fats because of a missing or poorly working enzyme called methylmalonyl-CoA epimerase (also known as methylmalonyl-CoA racemase). This enzyme normally helps convert one form of methylmalonyl-CoA into another form so it can be further processed in the body's energy pathways. When this enzyme does not work properly, a substance called methylmalonic acid builds up in the blood and urine. This condition belongs to the broader group of methylmalonic acidemias, but it is generally considered one of the milder forms. Some affected individuals may have few or no symptoms, while others can experience episodes of metabolic crisis — especially during illness or fasting — with symptoms such as vomiting, poor feeding, low energy, and developmental concerns. The long-term effects can vary widely from person to person. Because this condition is so rare, treatment is largely based on experience with other forms of methylmalonic acidemia. Management typically includes a special low-protein diet, avoidance of prolonged fasting, and close monitoring during illnesses. Some patients may benefit from vitamin B12 supplementation, though this is more relevant to other subtypes. Early diagnosis through newborn screening or metabolic testing can help guide treatment and improve outcomes.
Also known as:
Key symptoms:
Elevated methylmalonic acid in blood and urineVomitingPoor feeding in infancyLow energy or fatigueFailure to thrive or poor weight gainDevelopmental delayEpisodes of metabolic crisis during illnessLow muscle toneDehydration during illnessIrritability
Autosomal recessive
Passed on when both parents carry the same gene change; often skips generations
Variable
Can begin at different ages, from infancy through adulthood
FDA & Trial Timeline
2 eventsModernaTX, Inc. — PHASE1, PHASE2
ModernaTX, Inc. — PHASE1, PHASE2
Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.
Treatments
No FDA-approved treatments are currently listed for Methylmalonic acidemia due to methylmalonyl-CoA epimerase deficiency.
2 clinical trialsare actively recruiting — trials can provide access to cutting-edge therapies.
View clinical trials →Specialists
View all specialists →No specialists are currently listed for Methylmalonic acidemia due to methylmalonyl-CoA epimerase deficiency.
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 Methylmalonic acidemia due to methylmalonyl-CoA epimerase deficiency.
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Start the conversation →Latest news about Methylmalonic acidemia due to methylmalonyl-CoA epimerase deficiency
1 articlesCaregiver Resources
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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.How severe is my child's condition based on their enzyme levels and genetic results?,What specific dietary restrictions should we follow, and can we work with a metabolic dietitian?,What is the emergency protocol if my child becomes sick or cannot eat?,Should my child take any supplements such as carnitine or vitamin B12?,How often should we have follow-up blood and urine tests?,Are there any activities or situations we should avoid to prevent metabolic crises?,Should other family members be tested for this condition?
Common questions about Methylmalonic acidemia due to methylmalonyl-CoA epimerase deficiency
What is Methylmalonic acidemia due to methylmalonyl-CoA epimerase deficiency?
Methylmalonic acidemia due to methylmalonyl-CoA epimerase deficiency is an extremely rare inherited metabolic disorder. It is sometimes called methylmalonyl-CoA racemase deficiency. In this condition, the body has trouble breaking down certain proteins and fats because of a missing or poorly working enzyme called methylmalonyl-CoA epimerase (also known as methylmalonyl-CoA racemase). This enzyme normally helps convert one form of methylmalonyl-CoA into another form so it can be further processed in the body's energy pathways. When this enzyme does not work properly, a substance called methylma
How is Methylmalonic acidemia due to methylmalonyl-CoA epimerase deficiency inherited?
Methylmalonic acidemia due to methylmalonyl-CoA epimerase deficiency follows a autosomal recessive inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
Are there clinical trials for Methylmalonic acidemia due to methylmalonyl-CoA epimerase deficiency?
Yes — 2 recruiting clinical trials are currently listed for Methylmalonic acidemia due to methylmalonyl-CoA epimerase deficiency on UniteRare. See the clinical trials section on this page for phase, sponsor, and site details sourced from ClinicalTrials.gov.