It’s because of a genetic defect that prevents the body from properly processing certain proteins.
This metabolic dysfunction leads to a buildup of methylmalonic acid in the body.
Methylmalonic acidemia can cause coma and other serious symptoms if not correctly diagnosed and treated.
Verywell / JR Bee
This article explains the symptoms of methylmalonic acidemia and how it is passed down within families.
It also discusses how MMA is diagnosed and treated, along with some of the long-term impacts.
In the most severe cases, symptoms begin almost immediately at birth.
In others, they might not appear until later infancy, childhood, or even adulthood.
Many of the symptoms of methylmalonic acidemia get worse in particular situations.
Called decompensation of the illness, this may lead to life-threatening symptoms.
Infants are particularly at risk.
For example, someone with a mild form of methylmalonic acidemia might first experience kidney disease symptoms in adulthood.
What Causes Methylmalonic Acidemia?
Methylmalonic acidemia belongs in a group of disorders known asinborn errors of metabolism.
Metabolism refers to how the body converts nutrients in food into energy.
Inborn errors of metabolism are brought on by different genetic defects that lead to problems with metabolism.
Metabolism takes place through a complicated and highly coordinated sequence of chemical reactions.
Problems in many different genes may disrupt normal metabolic processes.
It results in unhealthy levels of products otherwise normally present in the body.
Defects in different enzymes lead to different types of organic aciduria.
Due to the defect in the gene, the resulting proteins dont work as well as they should.
These defects cause problems with the functioning of a specific protein enzyme, called methylmalonyl-CoA mutase.
Early diagnosis and management may then help prevent long-term complications from the disease.
Talking with a genetic counselor can be very helpful for many families.
This can give you a sense of the risks in your situation.
Prenatal testing may also be an option.
Also, infants might first experience symptoms before the results of these screening tests are available.
Diagnosis of methylmalonic acidemia requires a thorough medical history and exam.
Laboratory testing is critical as well.
It can be a challenge to rule out these other possible diagnoses and narrow down on the specific cause.
Since MMA is a rare condition, a medical specialist may be needed to help diagnose the disease.
One key diagnostic test for MMA looks at how much methylmalonic acid is present in the blood or urine.
In people with MMA, these levels should be higher than usual.
In some cases, this may affect treatment options.
These periods might happen before an initial diagnosis or at other times of stress or illness.
Intensive support in a hospital setting is necessary.
A dietary specialist who is experienced in rare metabolic diseases can help guide nutritional support.
Reducing the amount of protein consumed may reduce the impact of the disease.
However, limiting protein too severely has its own negative health impacts.
Thats why its helpful to work with a professional.
A feeding tube is also sometimes helpful to help ensure proper nutrition, especially during decompensations.
Other long-term medications might also be needed to treat complications.
For example, someone might need to take a bisphosphonate drug to help treat osteoporosis related to methylmalonic acidemia.
Liver transplant is also an option for some people with MMA.
Preventing Decompensations
Preventing decompensations is also an important part of treatment.
People with methylmalonic acidemia should not fast or increase their intake of protein because this might trigger a decompensation.
This can help prevent a decompensation.
Affected individuals need to be closely monitored whenever they are exposed to stressors that might trigger a decompensation.
That way, treatment can begin promptly if necessary.
Ideally, people with MMA should see a specialist with experience in rare genetic diseases.
Treatment and monitoring will require a range of medical professionals working together as a team.
Ask your healthcare provider if you are interested in participating in a clinical trial.
Or, check out the United States database for clinical trials.
A Word From Verywell
A diagnosis of methylmalonic acidemia can be challenging for many families.
Fortunately, both diagnosis and treatment have improved in recent years.
U.S. National Library of Medicine.Methylmalonic Acidemia - Genetics Home Reference - NIH.
Zhou X, Cui Y, Han J.Methylmalonic acidemia: Current status and research priorities.Intractable Rare Dis Res.
2013;23(2):245246.
PMID:23724196
Keyfi F, Talebi S, Varasteh AR.Methylmalonic Acidemia Diagnosis by Laboratory Methods.Rep Biochem Mol Biol.
2016;5(1):114.
PMID: 28070528
Fraser JL, Venditti CP.Methylmalonic and propionic acidemias: clinical management update.Curr Opin Pediatr.
2022 Mar;61(2):290-298. doi:10.1016/j.tjog.2022.02.017.
2020 Nov 14;25(22):5312. doi:10.3390/molecules25225312.
2017;25(11):11951201. doi:10.1038/ejhg.2017.127
Manoli I, Sloan JL, Venditti CP.Isolated Methylmalonic Acidemia.
In: Adam MP, Ardinger HH, Pagon RA, et al., editors.
GeneReviews [Internet].
Seattle (WA): University of Washington, Seattle; 1993-2019.
2022 Feb 9;10:824399. doi:10.3389/fped.2022.824399.
Chandler RJ, Venditti CP.Gene Therapy for Methylmalonic Acidemia: Past, Present, and Future.
2016;22(18):44384445. doi:10.3748/wjg.v22.i18.4438
U.S. National Library of Medicine.Clinical Trials.
Manoli I, Venditti CP.Disorders of branched chain amino acid metabolism.Translational Science of Rare Diseases.
2016;1(2):91-110. doi:10.3233/TRD-160009
