Summary about Disease
Methylmalonic acidemia (MMA) is a rare inherited metabolic disorder in which the body is unable to properly process certain amino acids and fats. This leads to a buildup of methylmalonic acid and other harmful substances in the blood, urine, and tissues. There are several different types of MMA, each caused by a specific genetic defect that affects the enzymes involved in the breakdown of these substances. MMA can lead to various health problems, ranging from mild to life-threatening.
Symptoms
Symptoms of MMA vary depending on the severity of the condition and the age of onset. Common symptoms include:
Poor feeding
Vomiting
Lethargy
Failure to thrive (poor weight gain and growth)
Developmental delays
Intellectual disability
Seizures
Muscle weakness (hypotonia)
Enlarged liver (hepatomegaly)
Kidney problems
Coma
Acidosis (high acid levels in the blood)
Elevated ammonia levels in the blood (hyperammonemia)
Causes
MMA is caused by genetic mutations in genes that provide instructions for making enzymes involved in the metabolism of methylmalonic acid. The specific gene affected depends on the type of MMA. These mutations disrupt the function of these enzymes, leading to the buildup of toxic substances. MMA is inherited in an autosomal recessive pattern, meaning that both parents must carry a copy of the mutated gene for their child to be affected.
Medicine Used
Treatment for MMA focuses on managing symptoms, preventing complications, and reducing the buildup of harmful substances. Medicines include:
Vitamin B12 (Cobalamin): Some forms of MMA respond to high doses of vitamin B12.
L-Carnitine: This helps to remove accumulated organic acids from the body.
Antibiotics: Used to reduce the amount of propionic acid produced by gut bacteria.
Sodium Bicarbonate or Sodium Citrate: Used to treat metabolic acidosis.
Ammonia scavengers (e.g., sodium benzoate, sodium phenylacetate): Used to reduce high ammonia levels. Dietary management is also crucial and typically includes a protein-restricted diet, often supplemented with special formulas. In some cases, liver or kidney transplantation may be considered.
Is Communicable
No, methylmalonic acidemia is not communicable. It is a genetic disorder caused by inherited gene mutations and cannot be spread from person to person.
Precautions
Precautions for individuals with MMA and their families include:
Strict adherence to dietary management: Following a low-protein diet as prescribed by a metabolic specialist.
Close monitoring of health status: Regular blood and urine tests to monitor methylmalonic acid and ammonia levels.
Prompt treatment of illness: Infections and other illnesses can trigger metabolic crises, so early medical intervention is essential.
Avoiding prolonged fasting: Fasting can exacerbate metabolic imbalances.
Genetic counseling: For families with a history of MMA, genetic counseling can help assess the risk of having another affected child.
Emergency protocol: Have a written emergency protocol to use in case of metabolic decompensation
How long does an outbreak last?
MMA isn't an outbreak-related disease. It's a chronic condition. However, metabolic crises can occur which will last until treatment is given.
How is it diagnosed?
Diagnosis of MMA typically involves:
Newborn screening: Many states include MMA in their newborn screening programs, which involves testing a small blood sample for elevated levels of methylmalonic acid.
Blood and urine tests: Elevated levels of methylmalonic acid in the blood and urine are suggestive of MMA.
Genetic testing: DNA analysis can identify specific gene mutations associated with MMA.
Enzyme assays: Measuring the activity of the affected enzyme in cells can confirm the diagnosis.
Ammonia Levels: Checking ammonia levels to assess the possible hyperammonemia and its treatment
Timeline of Symptoms
The timeline of symptoms varies depending on the severity of the condition:
Neonatal-onset (severe): Symptoms may appear within the first few days or weeks of life.
Late-onset (milder): Symptoms may not appear until later in infancy or childhood.
Adult-onset: Very rare. Symptoms in severe cases typically include poor feeding, vomiting, lethargy, and failure to thrive soon after birth. If left untreated, these symptoms can progress to seizures, coma, and even death. Milder cases may present with developmental delays or other nonspecific symptoms later in life.
Important Considerations
Early diagnosis and treatment are crucial: Prompt intervention can significantly improve the outcome for individuals with MMA.
Lifelong management is required: MMA is a chronic condition that requires ongoing monitoring and treatment.
Metabolic crises can occur: These are episodes of severe metabolic imbalance that can be life-threatening.
Dietary management is essential: A carefully controlled diet is critical for managing the condition.
Family support is important: Living with MMA can be challenging for both affected individuals and their families.
Research is ongoing: Scientists are working to develop new and improved treatments for MMA.