What are Propionic Acidemia and Methylmalonic Acidemia?
PROPIONIC ACIDEMIA:
AN ORGANIC ACID DISORDER
Propionic acidemia (PA) is a genetic disorder that is inherited by children from their parents. PA is caused by a deficiency of an enzyme called propionyl-CoA carboxylase (PCC). Complete or partial lack of PCC enzyme function makes it difficult for your body to break down and use things that your body needs.
METHYLMALONIC ACIDEMIA:
AN ORGANIC ACID DISORDER
Methylmalonic acidemia (MMA) is a genetic disorder that is inherited by children from their parents. The most common cause of MMA is a deficiency of an enzyme called methylmalonyl-CoA mutase (MUT). Another cause of MMA is a malfunctioning cofactor that cannot assist the MUT enzyme as it should. Complete or partial lack of MUT enzyme function makes it difficult for your body to break down and use things that your body needs.

Your body has difficulty using:

Certain amino acids (building blocks of protein)
Some types of fat that you get from the foods you eat
Chemicals made by bacteria in your gut
When PA or MMA prevents your body from breaking down and using certain substances, toxins can build up in your body.
HOW CAN PROPIONIC ACIDEMIA AND METHYLMALONIC ACIDEMIA AFFECT THE UREA CYCLE?
If you have PA or MMA, your body lacks sufficient PCC or MUT enzyme activity to break down and use certain amino acids and fats. This causes toxins to build up in your body. Some of these toxins can block or impair your body’s urea cycle. The urea cycle processes and removes the excess ammonia in your body that is produced during the breakdown of protein.

To start the urea cycle, your body needs a compound called N-acetylglutamate (NAG). But the toxic substances that build up in PA and MMA may lead to less NAG production. Without sufficient NAG, the urea cycle will not work properly, resulting in the build-up of ammonia in your blood.
Hyperammonemia that is caused by PA or MMA is called secondary hyperammonemia since the enzyme deficiencies that cause the disorders are not part of the urea cycle.
HOW IS HIGH BLOOD AMMONIA IN PROPIONIC ACIDEMIA AND METHYLMALONIC ACIDEMIA IDENTIFIED?
If your doctor suspects that you may have a high blood ammonia level as a result of PA or MMA, he or she will order a blood ammonia test. What is considered a “normal” blood ammonia level varies, based on your age.
HIGH AMMONIA LEVELS CAN BE DANGEROUS WHEN LEFT UNTREATED
At high levels, ammonia is toxic, especially to your brain. If left untreated, high blood ammonia levels can lead to brain damage or even death.
Any episode of acute hyperammonemia (high blood ammonia level) should be treated as a life-threatening emergency. Prompt use of all therapies necessary to lower blood ammonia levels is essential.
There are therapies available to help manage acute high blood ammonia levels due to PA or MMA.
Learn more about this supplemental treatment.
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