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# Propionic acidaemia

In propionic acidaemia propionyl-CoA is not processed; acids build up and cause acidosis crises, high ammonia and damage to heart and brain.

Updated 2026-11-01

## Structures involved

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- [Globus pallidus](https://durgical.com/en/anatomy/globus-pallidus/)
- [Left ventricle](https://durgical.com/en/anatomy/left-ventricle/)
- [Pancreas](https://durgical.com/en/anatomy/pancreas/)
- [Liver](https://durgical.com/en/anatomy/liver/)

## In biochemistry

- [Propionyl-CoA to succinyl-CoA: Step 1 · Propionyl-CoA carboxylase (PCC)](https://durgical.com/en/biochemistry/pathways/propionyl-coa-to-succinyl-coa/#paso-1)
- [Carbamoyl phosphate synthetase I (CPS-I)](https://durgical.com/en/biochemistry/enzymes/carbamoyl-phosphate-synthetase-i/)
- [Branched-chain α-keto acid dehydrogenase (BCKDH)](https://durgical.com/en/biochemistry/enzymes/branched-chain-keto-acid-dehydrogenase/)
- [Glucogenic and ketogenic amino acids](https://durgical.com/en/biochemistry/topics/glucogenic-and-ketogenic-amino-acids/)

## What it is

An inherited organic acidaemia from lack of propionyl-CoA carboxylase, a biotin-dependent enzyme.

## Who gets it

It affects about 1 in 100,000 people in the United States; it is more common in Saudi Arabia, some Amish communities and the Inuit of Greenland.

## Causes

- Variants of PCCA or PCCB (autosomal recessive)

## Risk factors

- Carrier parents
- Consanguinity
- Infections and fasting (crises)

## Pathophysiology

Propionyl-CoA carboxylase turns propionyl-CoA into methylmalonyl-CoA. Without it, propionyl-CoA, propionic acid, 3-hydroxypropionate and methylcitrate build up. There is high anion gap acidosis, hyperammonaemia (less N-acetylglutamate), bone marrow suppression and damage to basal ganglia and myocardium.

## Symptoms and signs

- Poor feeding, vomiting and lethargy in the first days
- Hypotonia and seizures
- Low neutrophils and platelets
- Developmental delay
- Later: cardiomyopathy and arrhythmias

## Red flags

- Encephalopathy with acidosis and high ammonia in a newborn
- Heart failure symptoms in a known patient
- Long QT

## Diagnosis

**Clinical**
Neonatal encephalopathy with acidosis; expanded newborn screening with high propionylcarnitine.

**Tests**
High propionylcarnitine (C3); urinary 3-hydroxypropionate, methylcitrate and propionylglycine, without high methylmalonic acid; ammonia, gases and blood count; genetic testing.

**Imaging**
Echocardiography for cardiomyopathy; brain MRI for basal ganglia lesions.

## Treatment

**Acute**
In a crisis: stop protein, give glucose and lipids, correct acidosis, carglumic acid or scavengers for ammonia, and dialysis if severe

**Lifestyle**
Low-protein diet with a formula free of valine, isoleucine, methionine and threonine

**Medical**
Carnitine and metronidazole to cut propionate made by gut bacteria

**Surgical**
[Liver](https://durgical.com/en/anatomy/liver/) transplant in selected cases

**Follow-up**
Cardiology follow-up with echocardiography and electrocardiography

## Complications

- Cardiomyopathy and long QT
- Pancreatitis
- Basal ganglia lesions
- Intellectual disability
- Infections from neutropenia

## Prognosis

Neonatal forms carry a high risk of death and sequelae; early diagnosis and dietary control improve survival.

## Test yourself

Think of the answer, then tap the question to see it.

## Which vitamin does propionyl-CoA carboxylase need?

Biotin (B7), like all carboxylases that fix CO₂.

## What separates propionic from methylmalonic acidaemia in urine?

In propionic acidaemia methylmalonic acid does not rise; methylcitrate and 3-hydroxypropionate do appear.

## Which heart complication is typical?

Cardiomyopathy, sometimes with long QT and arrhythmias, even with good metabolic control.

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## Related conditions

- [Methylmalonic acidaemia](https://durgical.com/en/conditions/methylmalonic-acidaemia/)
- [Hyperammonaemia](https://durgical.com/en/conditions/hyperammonaemia/)
- [Maple syrup urine disease](https://durgical.com/en/conditions/maple-syrup-urine-disease/)
- [Chronic kidney disease](https://durgical.com/en/conditions/chronic-kidney-disease/)
- [Acute pancreatitis](https://durgical.com/en/conditions/acute-pancreatitis/)
- [Heart failure](https://durgical.com/en/conditions/heart-failure/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Propionic acidemia: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/propionic-acidemia/) (MedlinePlus, US National Library of Medicine, 2026); [PCCA gene: MedlinePlus Genetics](https://medlineplus.gov/genetics/gene/pcca/) (MedlinePlus, US National Library of Medicine, 2026); [Propionyl-CoA catabolism](https://reactome.org/PathwayBrowser/#/R-HSA-71032) (Reactome, 2026).

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Source: https://durgical.com/en/conditions/propionic-acidaemia/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/propionic-acidaemia/