What Is Propionic Acidemia?

Symptoms, Causes, and Treatment of Propionic Acidemia

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Propionic acidemia is a rare and serious genetic disorder that affects multiple systems of the body, including the brain and heart. It is most often identified shortly after birth. In the United States, there are between 3,000 and 30,000 people living with the disorder.

Due to a genetic defect, the body is unable to properly process certain parts of proteins and fats. This ultimately leads to the symptoms of the condition. Without prompt diagnosis and treatment, it can cause coma and even death.

This article explains propionic acidemia symptoms and how it is diagnosed. It discusses treatment for the condition, other medical issues related to it, and general propionic acidemia life expectancy information.

propionic acidemia symptoms

Verywell / Emily Roberts

Propionic Acidemia Symptoms

Most often, the symptoms of propionic acidemia appear within a few days of birth. Infants are born healthy, but symptoms such as poor feeding and decreased responsiveness soon occur. Without prompt diagnosis and treatment, additional symptoms appear.

These symptoms include:

  • Worsening lethargy
  • Poor feeding and dehydration
  • Decreased muscle tone
  • Seizures (occurs in about 30% of cases)
  • Vomiting
  • Coma

Without diagnosis and acute intervention, death may soon follow.

Less commonly, symptoms might first appear later in childhood, or in adolescence or adulthood. Whenever it begins, propionic acidemia can also lead to more chronic problems.

These chronic problems include:

Causes

Propionic acidemia is a type of “inborn error of metabolism.” These are a group of individually rare diseases caused by different genetic defects. They lead to problems with metabolism, the process by which the nutrients in food are turned into energy.

Metabolism takes place through a complicated and highly coordinated sequence of chemical reactions, so problems in many different genes can lead to some sort of disruption of normal metabolic processes.

Propionic acidemia also belongs to a smaller subset of these diseases called organic acidurias. These genetic diseases result from difficulties metabolizing certain types of amino acids (the building blocks of protein) as well as some components of carbohydrates and fats.

Because of this, the levels of certain acids normally present in the body may begin to rise to unhealthy levels.

Defects in different enzymes lead to different types of organic aciduria. For example, maple syrup urine disease is another rare disease in this class. Its name is derived from a distinctive smell.

A fishy odor is known as the propionic acidemia smell, too, and is associated with one of its lifelong treatments.

Underlying Genetic Defect

Propionic acidemia is caused by a defect in one of two genes: PCCA or PCCB. These two genes make up the two components of an enzyme called propionyl-CoA carboxylase (PCC). Without this enzyme, the body is unable to properly metabolize certain amino acids, and some components of fats and cholesterol.

Is There a Cure for Propionic Acidemia?

Not yet. Researchers have identified the PCCA and PCCB genes, but as the science evolves they're learning that up to 70 types of genetic mutation may play some role. A cure may vary depending on the mutation, with some studies on gene therapy showing promising results for future treatment. For right now, the focus is on existing treatment for the condition.

Other propionic acidemia symptoms may be due to problems in producing energy because of the metabolic dysfunction.

Propionic acidemia is an autosomal recessive genetic condition. That means that a person has to inherit an affected gene from both of their parents to get the disease.

If a couple has had one child born with propionic acidemia, there is a 25% chance that their next child would also have the condition. It’s also important to test existing siblings whose symptoms may develop later. 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 and embryo selection may also be an option.

Diagnosis

Diagnosis of propionic acidemia requires a thorough medical history and medical exam, as well as laboratory testing. It’s important that diagnosis happens as quickly as possible since affected individuals are often very ill.

Many different types of medical problems can lead to the severe episodes of neurological and other symptoms seen in propionic acidemia, including other rare genetic diseases. Healthcare providers must rule out other possible diagnoses while they narrow in on the specific cause.

Lab Tests for Diagnosis

A wide range of laboratory tests is usually needed. Some of these might include:

  • Basic blood work (to assess for response to infection, anemia, glucose levels, basic organ function, etc.)
  • Blood work to assess various metabolites such as ammonia, lactic acid
  • A blood sample to assess for bacterial infection
  • Urinalysis (to assess for metabolites and infection)

People with propionic acidemia may also have abnormalities in more specialized tests. For example, people with the condition will show an elevation in a substance called propionylcarnitine.

Based on these initial tests, doctors work to confirm the diagnosis. This might include tests to assess how well the PCC enzyme is working. Genetic tests of the PCCA and the PCCB genes can also be used to finalize the diagnosis.

Sometimes, infants are first diagnosed from the results of standard newborn screening tests. However, not all states or countries around the world test for this specific disease. Also, infants may first experience symptoms before the results of these screening tests are available.

Treatment

Periods of acute illness from propionic acidemia are medical emergencies. Without support, individuals may die during these episodes. They may occur before an initial diagnosis or at other periods of stress or illness. These individuals need intensive support in a hospital setting.

People with propionic acidemia may need to be treated with:

  • Intravenous fluids and glucose
  • Insulin
  • Treatment of precipitating factors (like bacterial infection)
  • Tightly managed protein intake
  • Intravenous carnitine (enhances the removal of propionic acid through the urine)
  • Medications such as sodium benzoate (to remove toxic byproducts)
  • Ventilatory support, if necessary
  • Hemodialysis or extracorporeal membrane oxygenation (ECMO, to remove toxic byproducts)

How Long Can You Live With Propionic Acidemia?

People with propionic acidemia face many challenges and often have other medical conditions. For example, cardiomyopathy that emerges in childhood (at age 7, on average) accounts for many deaths. But each story is unique. With quality care, many people with propionic acidemia live full and longer lives. Specialists in rare genetic diseases, along with a team of healthcare providers, can help.

A Word From Verywell

Propionic acidemia often leads to a health crisis in just the first few days of life, which can feel overwhelming. It may take a while to process what is happening. It requires ongoing care but many people with propionic acidemia go on to lead full lives. Don’t hesitate to reach out to your friends, family members, and healthcare team for support.

9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Institutes of Health Genetic and Rare Diseases Information Center. Propionic Acidemia.

  2. NIH U.S. National Library of Medicine: Genetics Home Reference. Propionic Acidemia.

  3.  National Organization for Rare Disorders. Propionic Acidemia.

  4. Martín-Rivada Á, Palomino Pérez L, Ruiz-Sala P, Navarrete R, Cambra Conejero A, Quijada Fraile P, et al. Diagnosis of inborn errors of metabolism within the expanded newborn screening in the Madrid region. JIMD Rep. 2022 Jan 27;63(2):146-161. doi:10.1002/jmd2.12265.

  5. Propionic Acidemia Foundation. Treatments.

  6. Propionic Acidemia Foundation. Research.

  7. Forny P, Hörster F, Ballhausen D, Chakrapani A, Chapman KA, Dionisi-Vici C, et al. Guidelines for the diagnosis and management of methylmalonic acidaemia and propionic acidaemia: First revision. J Inherit Metab Dis. 2021 May;44(3):566-592. doi:10.1002/jimd.12370. 

  8. Fraser JL, Venditti CP. Methylmalonic and propionic acidemias: clinical management updateCurrent opinion in pediatrics. 2016;28(6):682-693. doi:10.1097/MOP.0000000000000422

  9. Alonso-Barroso E, Pérez B, Desviat LR, Richard E. Cardiomyocytes Derived from Induced Pluripotent Stem Cells as a Disease Model for Propionic Acidemia. Int J Mol Sci. 2021 Jan 25;22(3):1161. doi:10.3390/ijms22031161.

Additional Reading

By Ruth Jessen Hickman, MD
Ruth Jessen Hickman, MD, is a freelance medical and health writer and published book author.