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PubMed This is a summary of 22 peer-reviewed journal articles Updated
Metabolic medicine

Understanding Your Propionic Acidemia Diagnosis

At a Glance

Propionic acidemia is a lifelong inherited metabolic condition in which the body lacks enough of an enzyme needed to process certain food components, allowing toxic substances to build up. Care focuses on a tailored protein-controlled diet, medical formula, supplements, prompt illness treatment, and metabolic-team follow-up.

Receiving a diagnosis of Propionic Acidemia (PA) for your child is often a moment of profound emotional shock [1]. Whether the news came through a newborn screening report or during a frightening medical crisis in the hospital, it is natural to feel overwhelmed, confused, or even devastated [1][2].

PA is a rare genetic condition that changes how your child’s body processes certain parts of food, but it is also a condition that a dedicated team of specialists—and you, as their parent or caregiver—will learn to manage one step at a time [3]. This page will help you understand the biology of PA and what this diagnosis means for your child’s future.

What is Propionic Acidemia?

At its simplest, PA is a metabolic disorder, which means your child’s body has trouble turning specific parts of food into energy [4].

Specifically, your child is missing or has a very low level of an enzyme (a protein that triggers chemical reactions) called propionyl-CoA carboxylase (PCC) [4][5]. Normally, this enzyme acts like a pair of “chemical scissors,” breaking down four specific amino acids (parts of protein) and certain odd-chain fatty acids [4]. Without enough of these “scissors,” a substance called propionic acid and other related chemicals build up to toxic levels in the blood and organs [4][6].

Note: PA is not a general failure to digest all protein or fat. It only affects the specific breakdown pathways for these exact amino acids and fats.

The Genetic Cause

PA is an autosomal recessive condition [7]. This means that for a child to have PA, they must inherit two changed (mutated) copies of a specific gene—one from each parent [1].

  • The Genes: PA is caused by variants in either the PCCA gene or the PCCB gene [4]. These genes provide the instructions for making the two parts of the PCC enzyme [5].
  • The Parents: In almost all cases, parents are “carriers.” They have one working gene and one changed gene. Carriers usually have no symptoms because their one working gene produces enough enzyme for their own health [1].
  • Predicting Severity: While genetic testing confirms the diagnosis, the specific gene involved (PCCA vs. PCCB) does not always predict how severe the condition will be [8][9]. Residual enzyme activity varies, and two children with the same genetic variant may have different experiences [9].

Genetic Counseling: Because both parents are typically carriers, there is a 25% chance in every future pregnancy of having another child with PA. A genetic counselor can discuss family testing and reproductive options with you.

Two Ways PA Presents

Doctors generally describe PA based on when the first symptoms appear. It is important to know that early or late onset are not fixed severity categories—they simply describe when the condition was first noticed.

Early-Onset (Neonatal) Presentation

This is the most common time symptoms first appear [10]. Symptoms usually happen within the first few days or weeks of life and may include:

  • Poor feeding and vomiting [10].
  • Extreme sleepiness or difficulty waking up (lethargy) [10].
  • Low muscle tone (hypotonia) [10].
  • Hyperammonemia (high levels of ammonia in the blood), which can be life-threatening if not treated quickly [11].

Late-Onset Presentation

In some individuals, symptoms do not appear until later in infancy, childhood, or even adulthood [12]. These symptoms can be episodic, often triggered by an illness, fasting, or a high-protein meal [13]. Signs may include developmental delays, seizures, movement problems, or heart problems like cardiomyopathy (a weakening of the heart muscle) [13][14].

Managing Life with PA

While PA is a serious, lifelong condition, there are several treatments used to keep metabolic levels stable and protect health.

  • Dietary Management: This is the cornerstone of care. Caregivers must carefully measure “natural” protein, restricting the specific amino acids the body cannot process [15]. To ensure the body still gets the nutrients it needs to grow, a specialized medical formula is used [15][16].
  • Supplements: Many take levocarnitine (carnitine), a supplement that helps the body remove toxic byproducts from the blood [17].
  • Medications for Crisis: During times of illness, doctors may use specialized hospital medications (like carglumic acid) to rapidly lower ammonia levels [18][17].
  • Liver Transplantation: For some, a liver transplant may be considered [19]. While not a “cure,” a new liver provides a source of the missing enzyme, which can significantly stabilize the metabolism [19][20].

Looking Forward

The path ahead involves a new way of living, focused on careful nutrition and close partnership with a metabolic team [3]. Outcomes vary widely: some individuals meet developmental milestones with minimal hospitalizations, while others face more complex challenges with growth, heart health, or learning [8][21].

The most important thing to know today is that your medical team—including doctors, dietitians, and genetic counselors—is there to guide you through every lab result and dietary change [3][22]. This guide supplements, but never replaces, the individualized metabolic and emergency plan provided by your child’s doctors.

Common questions in this guide

How is propionic acidemia diagnosed, and what causes it?
Propionic acidemia may be identified through newborn screening or during a medical crisis, and genetic testing can confirm the diagnosis. It results from changes in either the PCCA or PCCB gene, which reduce activity of the enzyme that breaks down certain food components.
Does the PCCA or PCCB result predict how severe my child's PA will be?
Not reliably. Genetic testing confirms the diagnosis, but remaining enzyme activity and other factors mean that children with the same genetic variant can have different symptoms and care needs.
What symptoms can propionic acidemia cause?
Early-onset PA may cause poor feeding, vomiting, extreme sleepiness, low muscle tone, or high ammonia in the blood. Later-onset episodes may follow illness, fasting, or a high-protein meal and may involve developmental delays, seizures, movement problems, or heart muscle weakness.
How is PA managed from day to day?
Daily care usually includes carefully measured natural protein, a specialized medical formula, and close monitoring by a metabolic team. Levocarnitine may help remove toxic byproducts, while doctors may use medicines such as carglumic acid during a crisis.
What should I do if my child with PA stops eating or starts vomiting?
Illness, fasting, and vomiting can trigger a metabolic crisis and dangerous ammonia buildup. Follow your child's written emergency plan and contact the metabolic team or seek urgent medical care immediately rather than waiting for symptoms to resolve.
Can a liver transplant cure propionic acidemia?
A liver transplant may be considered for some children and can provide a source of the missing enzyme, which may make metabolism more stable. It is not a cure, and its benefits and risks must be weighed with the child's transplant and metabolic teams.
What is the chance of having another child with PA?
When both parents carry a changed copy of a PA-related gene, each pregnancy has a 25% chance of being affected. A genetic counselor can explain testing for family members and reproductive options.

Questions For You

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Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.What specific genes (PCCA or PCCB) are involved in my child's diagnosis, and what does that mean for their treatment?
  2. 2.Based on my child's initial labs and symptoms, what is the best way to monitor them moving forward?
  3. 3.How often will we need to monitor my child's ammonia and amino acid levels?
  4. 4.What is our specific emergency plan if my child stops eating or starts vomiting?
  5. 5.Is liver transplantation something we should consider in the future, and what are the benefits and risks for my child?
  6. 6.Can you refer us to a metabolic dietitian and a genetic counselor who has experience with PA?

References

References (22)
  1. 1

    Propionic acidemia identified in twin siblings conceived by in vitro fertilization (IVF) with parents who were unknown carriers of a PCCA mutation.

    Tian Y, Wang G, Shi W, Bai X

    BMC pregnancy and childbirth 2020; (20(1)):689 doi:10.1186/s12884-020-03391-z.

    PMID: 33183246
  2. 2

    Development of a signs and symptoms outcome measure for caregivers of patients with methylmalonic acidemia and propionic acidemia (MMAPAQ).

    Sikirica V, Schwartz EJ, Vockley J, et al.

    Molecular genetics and metabolism 2024; (143(1-2)):108577 doi:10.1016/j.ymgme.2024.108577.

    PMID: 39303317
  3. 3

    Assessing Gut Microbiota in an Infant with Congenital Propionic Acidemia before and after Probiotic Supplementation.

    Bordugo A, Salvetti E, Rodella G, et al.

    Microorganisms 2021; (9(12)) doi:10.3390/microorganisms9122599.

    PMID: 34946200
  4. 4

    Propionyl-CoA carboxylase - A review.

    Wongkittichote P, Ah Mew N, Chapman KA

    Molecular genetics and metabolism 2017; (122(4)):145-152 doi:10.1016/j.ymgme.2017.10.002.

    PMID: 29033250
  5. 5

    Generation of isogenic Propionyl-CoA carboxylase beta subunit (PCCB) deficient induced pluripotent stem cell lines.

    Pournasr B, Duncan SA

    Stem cell research 2020; (48()):101953 doi:10.1016/j.scr.2020.101953.

    PMID: 32822967
  6. 6

    Biochemical and anaplerotic applications of in vitro models of propionic acidemia and methylmalonic acidemia using patient-derived primary hepatocytes.

    Collado MS, Armstrong AJ, Olson M, et al.

    Molecular genetics and metabolism 2020; (130(3)):183-196 doi:10.1016/j.ymgme.2020.05.003.

    PMID: 32451238
  7. 7

    Novel variants of the PCCB gene in Chinese patients with propionic acidemia.

    Yang X, Li D, Tu C, et al.

    Clinica chimica acta; international journal of clinical chemistry 2021; (519()):18-25 doi:10.1016/j.cca.2021.03.019.

    PMID: 33798502
  8. 8

    Analysis of the relationship between phenotypes and genotypes in 60 Chinese patients with propionic acidemia: a fourteen-year experience at a tertiary hospital.

    Liu Y, Chen Z, Dong H, et al.

    Orphanet journal of rare diseases 2022; (17(1)):135 doi:10.1186/s13023-022-02271-3.

    PMID: 35331292
  9. 9

    Identification of 34 novel mutations in propionic acidemia: Functional characterization of missense variants and phenotype associations.

    Rivera-Barahona A, Navarrete R, García-Rodríguez R, et al.

    Molecular genetics and metabolism 2018; (125(3)):266-275 doi:10.1016/j.ymgme.2018.09.008.

    PMID: 30274917
  10. 10

    Current Perspectives on Neonatal Screening for Propionic Acidemia in Japan: An Unexpectedly High Incidence of Patients with Mild Disease Caused by a Common PCCB Variant.

    Tajima G, Kagawa R, Sakura F, et al.

    International journal of neonatal screening 2021; (7(3)) doi:10.3390/ijns7030035.

    PMID: 34203287
  11. 11

    The phenotypic spectrum of organic acidurias and urea cycle disorders. Part 1: the initial presentation.

    Kölker S, Garcia-Cazorla A, Cazorla AG, et al.

    Journal of inherited metabolic disease 2015; (38(6)):1041-57 doi:10.1007/s10545-015-9839-3.

    PMID: 25875215
  12. 12

    Propionic Acidemia with Novel Mutation Presenting as Recurrent Pancreatitis in a Child.

    Choe JY, Jang KM, Min SY, et al.

    Journal of Korean medical science 2019; (34(47)):e303 doi:10.3346/jkms.2019.34.e303.

    PMID: 31808324
  13. 13

    Novel compound heterozygous variants in the PCCB gene causing adult-onset propionic acidemia presenting with neuropsychiatric symptoms: a case report and literature review.

    Li Y, Wang M, Huang Z, et al.

    BMC medical genomics 2022; (15(1)):59 doi:10.1186/s12920-022-01202-2.

    PMID: 35296328
  14. 14

    Cardiac phenotype in propionic acidemia - Results of an observational monocentric study.

    Kovacevic A, Garbade SF, Hoffmann GF, et al.

    Molecular genetics and metabolism 2020; (130(1)):41-48 doi:10.1016/j.ymgme.2020.02.004.

    PMID: 32067920
  15. 15

    Long term follow-up of the dietary intake in propionic acidemia.

    Mobarak A, Stockler S, Salvarinova R, et al.

    Molecular genetics and metabolism reports 2021; (27()):100757 doi:10.1016/j.ymgmr.2021.100757.

    PMID: 33981581
  16. 16

    Methylmalonic and propionic acidemias: clinical management update.

    Fraser JL, Venditti CP

    Current opinion in pediatrics 2016; (28(6)):682-693 doi:10.1097/MOP.0000000000000422.

    PMID: 27653704
  17. 17

    Carglumic Acid Contributes to a Favorable Clinical Course in a Case of Severe Propionic Acidemia.

    Kido J, Matsumoto S, Nakamura K

    Case reports in pediatrics 2020; (2020()):4709548 doi:10.1155/2020/4709548.

    PMID: 32231837
  18. 18

    Role of carglumic acid in the long-term management of propionic and methylmalonic acidurias.

    Yap S, Gasperini S, Matsumoto S, Feillet F

    Orphanet journal of rare diseases 2024; (19(1)):464 doi:10.1186/s13023-024-03468-4.

    PMID: 39695809
  19. 19

    Liver Transplantation for Propionic Acidemia: Evidence From a Systematic Review and Meta-analysis.

    Zhou GP, Jiang YZ, Wu SS, et al.

    Transplantation 2021; (105(10)):2272-2282 doi:10.1097/TP.0000000000003501.

    PMID: 33093405
  20. 20

    Long Term Follow-Up After Transplantation in Propionic Acidemia: A Retrospective French Pediatric and Adult Cohort Study.

    Mekdade T, Bérat CM, Schiff M, et al.

    Journal of inherited metabolic disease 2026; (49(4)):e70216 doi:10.1002/jimd.70216.

    PMID: 42348330
  21. 21

    Propionic acidemia in Mexico: Clinical and genotypic spectrum.

    Vela-Amieva M, Alcántara-Ortigoza MA, Guillén-López S, et al.

    Molecular genetics and metabolism reports 2026; (47()):101311 doi:10.1016/j.ymgmr.2026.101311.

    PMID: 42021870
  22. 22

    Biochemical and genetic approaches to the prenatal diagnosis of propionic acidemia in 78 pregnancies.

    Dai M, Xiao B, Zhang H, et al.

    Orphanet journal of rare diseases 2020; (15(1)):276 doi:10.1186/s13023-020-01539-w.

    PMID: 33028371

This page is for informational purposes only and does not constitute medical advice. It explains propionic acidemia in children, but your child's metabolic team must guide diagnosis, emergency care, diet, and treatment.