Overview
Vitamin B12-unresponsive methylmalonic acidemia type mut0 is a serious inherited metabolic disorder. It is also known as MMA mut0 or methylmalonic aciduria mut0. In this condition, the body cannot properly break down certain proteins and fats because of a complete lack of function of an enzyme called methylmalonyl-CoA mutase. This enzyme normally needs vitamin B12 (cobalamin) to work, but in the mut0 form, the enzyme is so severely affected that even giving extra vitamin B12 does not help — hence the name "B12-unresponsive." When this enzyme does not work, a substance called methylmalonic acid builds up in the blood and body tissues. This buildup is toxic and can damage many organs, especially the brain, kidneys, and liver. Babies with this condition typically become very sick in the first days or weeks of life. Symptoms can include poor feeding, vomiting, extreme tiredness, low muscle tone, breathing problems, and seizures. Without prompt treatment, the condition can be life-threatening. Treatment focuses on limiting the intake of proteins that the body cannot process, using special medical formulas, and providing emergency care during metabolic crises. Some patients may eventually need a kidney or liver transplant. Despite treatment, many patients face ongoing challenges including developmental delays, kidney disease, and episodes of metabolic crisis throughout their lives. The mut0 form is generally considered the most severe type of methylmalonic acidemia because the enzyme has no residual activity at all.
Also known as:
Key symptoms:
Poor feeding or refusal to eatRepeated vomitingExtreme tiredness and lethargyLow muscle tone (floppy baby)Failure to grow and gain weightDevelopmental delaysIntellectual disabilitySeizuresKidney problems or kidney failureEpisodes of metabolic crisis with severe illnessBreathing difficultiesLow blood counts (anemia, low white cells, low platelets)Movement problemsLiver enlargementDehydration
Clinical phenotype terms (22)— hover any for plain English
Autosomal recessive
Passed on when both parents carry the same gene change; often skips generations
Neonatal
Begins at or shortly after birth (first 4 weeks)
Treatments
No FDA-approved treatments are currently listed for Vitamin B12-unresponsive methylmalonic acidemia type mut0.
View clinical trials →Clinical Trials
View all trials with filters →No actively recruiting trials found for Vitamin B12-unresponsive methylmalonic acidemia type mut0 at this time.
New trials open frequently. Follow this disease to get notified.
Specialists
View all specialists →No specialists are currently listed for Vitamin B12-unresponsive methylmalonic acidemia type mut0.
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 Vitamin B12-unresponsive methylmalonic acidemia type mut0.
Community
No community posts yet. Be the first to share your experience with Vitamin B12-unresponsive methylmalonic acidemia type mut0.
Start the conversation →Latest news about Vitamin B12-unresponsive methylmalonic acidemia type mut0
No recent news articles for Vitamin B12-unresponsive methylmalonic acidemia type mut0.
Follow this condition to be notified when news becomes available.
Caregiver Resources
NORD Caregiver Resources
Support, advocacy, and financial assistance for caregivers of rare disease patients.
Mental Health Support
Rare disease caregiving can be isolating. Connect with counseling and peer support.
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 child's specific genetic mutation, and what does it mean for the severity of the disease?,What should our emergency sick day plan look like, and when should we go to the emergency room?,How often should kidney function and other blood tests be monitored?,Is liver or kidney transplantation something we should consider, and when?,Are there any clinical trials for gene therapy or other new treatments that my child might be eligible for?,What developmental therapies and educational supports should we arrange?,How can we work with a metabolic dietitian to make sure our child gets proper nutrition while staying safe?
Common questions about Vitamin B12-unresponsive methylmalonic acidemia type mut0
What is Vitamin B12-unresponsive methylmalonic acidemia type mut0?
Vitamin B12-unresponsive methylmalonic acidemia type mut0 is a serious inherited metabolic disorder. It is also known as MMA mut0 or methylmalonic aciduria mut0. In this condition, the body cannot properly break down certain proteins and fats because of a complete lack of function of an enzyme called methylmalonyl-CoA mutase. This enzyme normally needs vitamin B12 (cobalamin) to work, but in the mut0 form, the enzyme is so severely affected that even giving extra vitamin B12 does not help — hence the name "B12-unresponsive." When this enzyme does not work, a substance called methylmalonic aci
How is Vitamin B12-unresponsive methylmalonic acidemia type mut0 inherited?
Vitamin B12-unresponsive methylmalonic acidemia type mut0 follows a autosomal recessive inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Vitamin B12-unresponsive methylmalonic acidemia type mut0 typically begin?
Typical onset of Vitamin B12-unresponsive methylmalonic acidemia type mut0 is neonatal. Age of onset can vary across affected individuals.