Sandeep Dhand
Nutritionist And Health Educator
Methylmalonic Acidemia (MMA) is a rare genetic disorder that affects how the body breaks down certain proteins and fats. It happens due to a missing or defective enzyme, causing harmful substances to build up in the blood. If left untreated, MMA can lead to serious health problems, including kidney failure, developmental delays, and even life-threatening conditions.
In this guide, we will cover everything you need to know about MMA, including its causes, symptoms, diagnosis, treatment, and a special diet plan for people with this condition.
What is Methylmalonic Acidemia (MMA)?
Methylmalonic Acidemia (MMA) is a metabolic disorder, which means it affects how the body processes food into energy. Normally, the body uses an enzyme called methylmalonyl-CoA mutase to break down certain amino acids and fats. However, in people with MMA, this enzyme is either missing or not working properly, leading to a buildup of toxic substances.
These toxins can damage organs like the brain, liver, and kidneys, causing serious health issues. MMA usually appears in infants but can also be diagnosed later in life.
Causes of MMA
MMA is a genetic disorder, meaning it is inherited from both parents. If both parents carry a defective gene, their child has a 25% chance of having MMA.
Types of MMA:
There are several types of MMA, depending on which part of the metabolic process is affected:
- Vitamin B12-Responsive MMA – Some cases of MMA can be treated with vitamin B12 supplements.
- Vitamin B12-Nonresponsive MMA – This form does not improve with vitamin B12 and requires stricter treatment.
- Mut0 and Mut- MMA – These types occur when the methylmalonyl-CoA mutase enzyme is completely absent (Mut0) or partially defective (Mut-).
- MMA with Homocystinuria – A combined disorder affecting metabolism and other biochemical processes.
Symptoms of MMA
Symptoms of MMA can appear within the first few days or weeks of life. In some cases, they may develop later in childhood or even adulthood.
Common Symptoms in Infants:
Poor feeding
Vomiting
Dehydration
Weak muscle tone (hypotonia)
Developmental delays
Breathing problems
Seizures
Lethargy (extreme tiredness)
Symptoms in Older Children and Adults:
Growth problems
Intellectual disability
Kidney disease
Liver problems
Vision and hearing issues
Difficulty walking or muscle weakness
Severe cases of MMA can lead to metabolic crises, where toxic substances build up quickly in the blood. This can cause coma, organ failure, or even death if not treated in time.
How is MMA Diagnosed?
MMA is usually detected through newborn screening tests, which check for rare genetic disorders right after birth. However, if MMA is not detected at birth, doctors may use other tests to confirm it later.
Tests for MMA:
- Blood Tests: To check for high levels of methylmalonic acid.
- Urine Tests: To detect metabolic byproducts.
- Genetic Testing: To identify defective genes.
- Enzyme Tests: To see if the methylmalonyl-CoA mutase enzyme is working properly.
- MRI or Brain Scans: To check for brain damage caused by toxic buildup.
If MMA is diagnosed early, treatment can prevent severe complications and improve quality of life.
Treatment for MMA
There is no complete cure for MMA, but early treatment can help manage symptoms and prevent complications. The main treatments include dietary changes, medications, and in some cases, organ transplants.
Diet Plan for MMA
A low-protein diet is the most important part of managing MMA. Since the body cannot break down certain amino acids, limiting protein intake prevents toxic buildup.
Foods to Avoid (High-Protein Foods):
Meat (chicken, beef, pork, fish)
Dairy products (milk, cheese, yogurt)
Eggs
Nuts and seeds
Soy products
Beans and lentils
Foods That Are Safe (Low-Protein Foods):
Fruits (apples, bananas, berries, oranges)
Vegetables (carrots, potatoes, cucumbers, spinach)
Rice, pasta, and bread (low-protein versions)
Special low-protein milk and dairy substitutes
Sugar and honey (in moderation)
Protein Substitutes:
Since protein is essential for growth, doctors may prescribe special medical formulas or amino acid supplements that provide safe levels of protein.
B. Vitamin B12 Treatment
Some types of MMA respond to vitamin B12 injections (hydroxocobalamin). If the patient’s body can use B12, this treatment helps reduce methylmalonic acid levels and prevents severe symptoms.
C. Medications for MMA
Doctors may prescribe:
Carnitine supplements – Helps remove toxins from the body.
Sodium bicarbonate – Balances the body’s acid levels.
Antibiotics – Reduces bacteria that produce methylmalonic acid in the gut.
D. Organ Transplants
In severe cases, a liver or kidney transplant may be needed. Since the liver plays a key role in breaking down amino acids, a new liver can improve metabolism and reduce MMA symptoms.
Long-Term Outlook for People with MMA
With proper treatment, many people with MMA can live relatively normal lives. However, lifelong management is needed to prevent complications.
Possible Long-Term Complications:
Kidney disease (may require dialysis or a transplant)
Learning difficulties and developmental delays
Growth problems
Frequent hospitalizations due to metabolic crises
Tips for Managing MMA:
Regular doctor visits – Keep track of metabolic levels.
Strict diet – Follow a low-protein meal plan.
Avoid infections – Illnesses can trigger metabolic crises.
Stay hydrated – Drink plenty of fluids to help the kidneys.
MMA and Pregnancy: Special Considerations
Women with MMA who become pregnant need extra care. Pregnancy increases the body’s metabolic demands, which can worsen MMA symptoms. Close monitoring, a specialized diet, and medical support are needed to ensure a safe pregnancy.
Research and Future Treatments
Scientists are working on new treatments for MMA, including:
Gene therapy – Fixing defective genes to restore enzyme function.
Enzyme replacement therapy – Providing the missing enzyme through medications.
Stem cell therapy – Using healthy cells to improve metabolism.
While these treatments are still experimental, they offer hope for a better future for MMA patients.
Conclusion
Methylmalonic Acidemia (MMA) is a serious but manageable disorder. With early diagnosis, a strict diet, and proper medical care, people with MMA can lead healthy and fulfilling lives.
If you or someone you know has MMA, work closely with doctors, follow a personalized diet plan, and stay informed about new treatments. Ongoing research is improving care options, bringing hope for better treatments and a possible cure in the future.