EARLY SIGNS
Signs of methylmalonic acidemia (MUT) can start at any time from birth to adulthood. In most cases, the signs begin during infancy (either in the first few days or in the first few months of life).
For babies, signs of MUT can include:
- Sleeping longer or more often
- Tiredness
- Vomiting
- Weak muscle tone (also called hypotonia)
- Fever
- Breathing trouble
- Increased number of illnesses and infections
- Increased bleeding and bruising
CAUSES
When we eat food, enzymes help break it down. Some enzymes break down proteins into their building blocks, amino acids. Other enzymes break down fats into their building blocks, fatty acids. More enzymes break down these amino acids and fatty acids.
In methylmalonic acidemia, the enzyme methylmalonyl-CoA mutase is not working correctly. This enzyme helps break down odd-chain fatty acids and the amino acids isoleucine, valine, methionine, and threonine. If your baby is affected with MUT, then his or her body is either not making enough or making non-working methylmalonyl-CoA mutase enzymes.
In “Mut 0” forms of MUT, this enzyme is completely deficient. That means that there are no working methylmalonyl-CoA mutase enzymes in the body. In “Mut –“ forms, some methylmalonyl-CoA mutase enzymes work correctly, but there are not enough. Without enough working enzymes, your baby’s body has trouble using fats and proteins for energy.
MUT is an autosomal recessive genetic condition. This means that a child must inherit two copies of the non-working gene for MUT, one from each parent, in order to have the condition. The parents of a child with an autosomal recessive condition each carry one copy of the non-working gene, but they typically do not show signs and symptoms of the condition. While having a child with MUT is rare, when both parents are carriers, they can have more than one child with the condition.
TREATMENT
There are two types of methylmalonic acidemia: cobalamin disorders and methylmalonic-CoA mutase (MUT) deficiencies. Cobalamin disorders are considered vitamin B-12 responsive. MUT deficiencies are non-vitamin B-12 responsive. You may hear about other babies with methylmalonic acidemia receiving vitamin B-12 injections. This treatment will not help a baby with methylmalonyl-CoA mutase deficiency.
Supplements and Medications
Your baby’s doctor might recommend L-carnitine supplements. These supplements help the body break down fats, and they can remove harmful substances from the body. Your baby’s doctor will need to write a prescription for these supplements.
Antibiotics can also help reduce methylmalonic acid levels.
Dietary Treatments
Your baby will need a very carefully monitored diet. Children with methylmalonic acidemia need to avoid certain fats and proteins because their bodies cannot break down these substances, causing a build up of toxic substances. Your doctor can recommend special formulas and foods made for children with organic acid conditions. These formulas will likely need to be continued through adulthood.
It is also important for your baby to eat frequently. Long periods of time without food, illness, or infections may trigger many of the signs mentioned in the Early Signs section.
EXPECTED OUTCOMES
Babies who receive treatment early on can have typical development and healthy lives. The earlier you start treatment, the better the outcome will be for your child.
It is possible to have some long-term effects even with treatment for methylmalonic acidemia (MUT) such as learning disabilities and developmental delays.
It is important to screen for and to treat MUT. If MUT is left untreated, children can develop breathing problems or permanent brain damage.