What is the definition of Methylmalonyl Coenzyme A Mutase Deficiency?
Methylmalonyl-Coenzyme A mutase deficiency (MCM deficiency) is a type of methylmalonic acidemia caused by having too little methylmalonyl-CoA mutase. Methylmalonyl-CoA mutase (MCM) is one of the special proteins (enzymes) needed to breakdown certain amino acids found in the food we eat. It is needed to breakdown certain fats too. When the amino acids and fats are not broken down normally, substances which are harmful to the body (including methylmalonic acid) build up and can damage the nervous system, kidneys and other organs. Symptoms of MCM deficiency usually begin in infancy or early childhood and may include tiredness (fatigue), vomiting, dehydration, weak muscle tone (hypotonia), fever, breathing trouble, frequent illnesses and infections, and increased bleeding and bruising. Long term complications include developmental delay, intellectual disability, enlarged liver (hepatomegaly), chronic kidney disease, inflammation of the pancreas (pancreatitis), and in severe cases coma and death.
Methylmalonyl-Coenzyme A mutase deficiency (MCM deficiency) is caused by changes or mutations in the MUT gene which can cause no enzyme to be produced (MUT0) or less than normal amounts of the enzyme to be made (MUT-). The more working enzyme that is made, the less severe the symptoms will be. MCM deficiency is inherited in an autosomal recessive manner. Diagnosis is made based on symptoms, special blood tests and genetic testing. Unlike some types of methylmalonic acidurias, B12 supplements are not helpful. Instead treatment includes a special diet low in proteins containing the amino acids isoleucine, methionine, threonine and valine and certain fats but high in calories. Other symptoms are treated as needed.
What are the alternative names for Methylmalonyl Coenzyme A Mutase Deficiency?
- MCM Deficiency
- Vitamin B12-unresponsive methylmalonic acidemia
- Methylmalonic aciduria due to methylmalonyl-CoA mutase deficiency
- Methylmalonic aciduria, mut TYPE
What are the current treatments for Methylmalonyl Coenzyme A Mutase Deficiency?
In 2014, guidelines for managment of methylmalonyl-Coenzyme A mutase deficiency (MMC deficiency) were published by professionals across 12 European countries and the United States. These guidelines are based on a review of published medical studies and expert group meetings. The guidelines may be hard to read without a medical background but can be shared with the affected person's doctor or other trusted medical professional: Proposed guidelines for the diagnosis and management of methylmalonic and propionic acidemia
What is the outlook (prognosis) for Methylmalonyl Coenzyme A Mutase Deficiency?
The threat of metabolic attacks caused by methylmalonyl-Coenzyme A mutase deficieny (MCM deficiency) is lifelong even if the diet is well controlled, but the number and severity of attacks depend on several factors including the amount of working MCM enzyme present and diet. Those with no MCM enzyme (MUT0) have a higher risk of complications and attacks. Those with some working MCM enzyme have less risk of complications, but may still have attacks when ill, stressed, fasting for long periods, or eating too much protein containing the amino acids isoleucine, methionine, threonine and valine.
The life expectancy for people with MCM deficiency has been improving due to early diagnosis and better understanding of dietary requirements and metabolic attack triggers and treatment. Life threatening complications are more common for those with MUT0. However medical researchers are working on several promising treatments.