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# Tyrosinaemia type I (hepatorenal)

In tyrosinaemia type I tyrosine breakdown stops at its last step and toxins form that damage the liver, [kidney](https://durgical.com/en/anatomy/kidney/) and nerves.

Updated 2026-11-01

## Structures involved

Tap one to see what it is and open it in 3D.

- [Liver](https://durgical.com/en/anatomy/liver/)
- [Kidneys](https://durgical.com/en/anatomy/kidney/)
- [Portal vein](https://durgical.com/en/anatomy/hepatic-portal-vein/)
- [Spleen](https://durgical.com/en/anatomy/spleen/)

## In biochemistry

- [Phenylalanine and tyrosine metabolism: Step 3 · 4-Hydroxyphenylpyruvate dioxygenase (HPPD)](https://durgical.com/en/biochemistry/pathways/phenylalanine-and-tyrosine-metabolism/#paso-3)
- [Phenylalanine and tyrosine metabolism: Step 6 · Fumarylacetoacetate hydrolase (FAH)](https://durgical.com/en/biochemistry/pathways/phenylalanine-and-tyrosine-metabolism/#paso-6)
- [Tyrosine](https://durgical.com/en/biochemistry/molecules/tyrosine/)

## What it is

An inherited disease from lack of fumarylacetoacetate hydrolase, the last enzyme of tyrosine breakdown.

## Who gets it

It affects about 1 in 100,000 people worldwide; it is much more common in Quebec (Canada), especially the Saguenay-Lac-Saint-Jean region, and in Norway.

## Causes

- Variants in both alleles of the FAH gene (autosomal recessive)

## Risk factors

- Carrier parents
- Populations with a founder effect

## Pathophysiology

Fumarylacetoacetate and maleylacetoacetate build up and turn into succinylacetone. These molecules damage hepatocytes and the proximal tubule and promote mutations (hepatocellular carcinoma). Succinylacetone inhibits ALA dehydratase of haem synthesis and causes porphyria-like neurological crises.

## Classification

- Acute: liver failure in the first months
- Chronic: cirrhosis, rickets and tubulopathy in the first year or later

## Symptoms and signs

- Failure to thrive and vomiting
- Jaundice, hepatomegaly and easy bleeding
- Rickets from renal phosphate loss (Fanconi syndrome)
- Boiled-cabbage odour
- Crises of pain and weakness from neuropathy

## Red flags

- Liver failure in an infant
- Coagulopathy with only mildly raised transaminases
- Liver nodules on follow-up

## Diagnosis

**Clinical**
An infant with [liver](https://durgical.com/en/anatomy/liver/) failure or tubulopathy; many cases are found by expanded newborn screening.

**Tests**
Succinylacetone in blood or urine (diagnostic); high plasma tyrosine and methionine; very high alpha-fetoprotein; FAH gene testing.

**Imaging**
Liver ultrasound and MRI to look for nodules and hepatocellular carcinoma.

## Treatment

**Medical**
Nitisinone, which blocks 4-hydroxyphenylpyruvate dioxygenase and prevents the toxins from forming

**Lifestyle**
Low-tyrosine, low-phenylalanine diet with a special formula

**Surgical**
Liver transplant for liver failure that does not respond, or carcinoma

**Follow-up**
Follow-up of succinylacetone, tyrosine, alpha-fetoprotein and liver imaging

## Complications

- Liver failure
- Cirrhosis and hepatocellular carcinoma
- Rickets and renal tubulopathy
- Neurological crises

## Prognosis

With early nitisinone, survival and cancer risk are much better than in the era before it.

## Prevention

- Newborn screening with succinylacetone
- Genetic counselling

## Test yourself

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

## Which enzyme is missing in tyrosinaemia type I?

Fumarylacetoacetate hydrolase, the last step of tyrosine breakdown.

## Which metabolite is diagnostic?

Succinylacetone in blood or urine.

## How does nitisinone work?

It inhibits 4-hydroxyphenylpyruvate dioxygenase, an earlier step, so fumarylacetoacetate and succinylacetone are not formed.

## Why are there porphyria-like crises?

Succinylacetone inhibits ALA dehydratase, and neurotoxic δ-aminolevulinic acid builds up.

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## Related conditions

- [Alkaptonuria](https://durgical.com/en/conditions/alkaptonuria/)
- [Hepatocellular carcinoma](https://durgical.com/en/conditions/hepatocellular-carcinoma/)
- [Cirrhosis](https://durgical.com/en/conditions/cirrhosis/)

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

Sources: [Tyrosinemia: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/tyrosinemia/) (MedlinePlus, US National Library of Medicine, 2026); [FAH gene: MedlinePlus Genetics](https://medlineplus.gov/genetics/gene/fah/) (MedlinePlus, US National Library of Medicine, 2026); [Tyrosine catabolism](https://reactome.org/PathwayBrowser/#/R-HSA-8963684) (Reactome, 2026).

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