Propionic acidemia is a rare and serious genetic disorder that affects multiple body systems, including the brain and heart. Most often it is discovered shortly after birth. It affects 3,000 to 30,000 people in the United States.
        Due to genetic defects, the body cannot properly process certain parts of proteins and fats. This eventually leads to the symptoms of the condition. If not diagnosed and treated in time, it can lead to coma and even death.
        This article explains the symptoms of propionic acidemia and how to diagnose it. It discusses the treatment of this condition, other medical issues associated with it, and general information about life expectancy for propionic acidemia.
        In most cases, symptoms of propionic acidemia appear within a few days of birth. Babies are born healthy but soon show symptoms such as poor nutrition and reduced response. If it is not diagnosed and treated, other symptoms may develop.
        Less commonly, symptoms may first appear in late childhood, adolescence, or adulthood. Propionic acidemia can also lead to more chronic problems, no matter when it starts.
        Propionic acidemia is a “congenital error of metabolism”. This is a group of rare diseases caused by various genetic defects. They can cause problems with metabolism, the process by which nutrients in food are converted into energy.
       Metabolism occurs through a series of complex and well-coordinated chemical reactions, so problems with many different genes can lead to some disruption of normal metabolic processes.
        Propionic acidemia also belongs to a subset of these disorders called organic aciduria. These genetic disorders result from impaired metabolism of certain types of amino acids (the building blocks of proteins) and certain components of carbohydrates and fats.
       As a result, the levels of some acids normally present in the body may begin to rise to unhealthy levels.
        Defects in different enzymes cause different types of organic aciduria. For example, maple syrup disease is another rare disease in this category. It got its name from its characteristic smell.
       The fishy odor is also known as propionic acidemia odor and has been linked to one of his lifelong treatments.
        Propionic acidemia is caused by a defect in one of two genes: PCCA or PCCB. These two genes form two components of an enzyme called propionyl-CoA carboxylase (PCC). Without this enzyme, the body cannot properly metabolize certain amino acids and certain components of fat and cholesterol.
        Not yet. Researchers had already identified the PCCA and PCCB genes, but as the science progressed, they learned that up to 70 genetic mutations could play a role. Treatment can vary depending on the mutation, and some gene therapy studies have shown promising results for future therapies. Currently, the focus is on existing treatments for this disease.
       Other symptoms of propionic acidemia may include problems with energy production due to metabolic dysfunction.
        Propionic acidemia is an autosomal recessive genetic disease. This means that a person must inherit the affected gene from their parents in order to develop the disease.
        If a couple has a child born with propionic acidemia, there is a 25 percent chance that the next child will also have the disease. It is also important to check on existing siblings who may develop symptoms later. Early diagnosis and treatment can help prevent long-term complications of the disease.
        Talking to a genetic counselor can be very helpful for many families. This will allow you to understand the risks of your situation. Prenatal testing and embryo selection may also be options.
        The diagnosis of propionic acidemia requires a thorough history and physical examination, as well as laboratory tests. It is important to make a diagnosis as soon as possible, as those affected are often very ill.
        Many different types of medical problems can cause the severe neurological symptoms and other symptoms seen in propionic acidemia, including other rare genetic disorders. Healthcare professionals should rule out other possible diagnoses by narrowing down the specific cause.
        People with propionic acidemia may also have abnormalities on more specialized tests. For example, people with this disorder have elevated levels of a substance called propionylcarnitine.
        Based on these initial tests, doctors work to confirm the diagnosis. This may include tests to evaluate how well the PCC enzyme is working. Genetic testing of the PCCA and PCCB genes can also be used to clarify the diagnosis.
        Sometimes infants are first diagnosed based on the results of standard newborn screening tests. However, not all states or countries around the world test for this particular disease. In addition, infants may show symptoms before the results of these screening tests are available.
        Acute illness caused by propionic acidemia is a medical emergency. Without support, people can die during these events. They may occur before the initial diagnosis or during times of stress or illness. These people need intensive support in a hospital setting.
        People with propionic acidemia face many problems and often have other medical conditions. For example, cardiomyopathy that develops in childhood (mean age 7 years) is the cause of many deaths. But every story is unique. With quality care, many people with propionic acidemia can live fuller and longer lives. A team of rare genetic disease specialists and healthcare professionals can help.
        Propionic acidemia often leads to a health crisis in the first few days of life that can feel overwhelming. The process of processing what is happening may take some time. It requires constant care, but many people with propionic acidemia go on to live full lives. Feel free to reach out to friends, family, and medical staff for support.
        Martin-Rivada A., Palomino Perez L., Ruiz-Sala P., Navarrete R., Cambra Conejero A., Quijada Fraile P. and others. Diagnosis of congenital metabolic disorders in expanded neonatal screening in the Madrid region. JIMD Report 2022 Jan 27; 63(2): 146–161. doi: 10.1002/jmd2.12265.
        Forney P, Hörster F, Ballhausen D, Chakrapani A, Chapman KA, Dionysi-Vici S, et al. Guidelines for the diagnosis and treatment of methylmalonic and propionic acidemia: a first revision. J inherited the Dis metab. May 2021; 44(3):566-592. doi: 10.1002/jimd.12370.
        Fraser JL, Venditti CP. Methylmalonic acid and propionic acidemia: a clinical management update. Current opinion in pediatrics. 2016;28(6):682-693. doi:10.1097/MOP.0000000000000422
        Alonso-Barroso E, Pérez B, Desviat LR, Richard E. Cardiomyocytes derived from induced pluripotent stem cells as a model for propionic acidemia disease. Int J Mol Sci. 2021 January 25; 22 (3): 1161. Home office: 10.3390/ijms22031161.
        Grünert SC, Müllerleile S, De Silva L, et al. Propionic acidemia: clinical course and outcomes in 55 children and adolescents. Orphanet J Rare Dis. 2013;8:6. doi: 10.1186/1750-1172-8-6
       Author: Ruth Jessen Hickman, MD Ruth Jessen Hickman, MD, is a freelance medical and health writer and author of published books.