Leigh Syndrome: French-Canadian Type


What is Leigh syndrome, French-Canadian type?

Leigh syndrome, French-Canadian type (LSFC), is a subtype of Leigh syndrome, and is a severe neurologic disorder caused by the deficiency of the enzyme COX. This condition is characterized by progressive loss of mental and movement abilities starting in the first year of life. Symptoms include low muscle tone, difficulty coordinating movement, and development of tissue damage in the brain. A distinctive facial appearance is present at birth. Affected individuals tend to have episodic crises triggered by severe illness or infections in early childhood where symptoms may worsen and are accompanied by difficulty breathing, seizures, coma, and often lead to early death. Some individuals survive into early childhood but typically have intellectual disability. There is no cure for LSFC; however medical surveillance and care may help to improve some symptoms and overall condition of life. This disease is caused by pathogenic variants in LRPPRC gene.

How is Leigh syndrome, French-Canadian type inherited?


What does it mean to be a carrier?

There are generally no signs or symptoms associated with being a carrier for LSFC. However, the risk to have a child affected with LSFC is increased. Testing of reproductive partners is recommended for carriers of LSFC syndrome.

How common is Leigh syndrome, French-Canadian type?

In the Saguenay-Lac St-Jean region of Quebec, LSFC affects 1 in 2,000 newborns. Outside of Quebec, Leigh syndrome affects at least 1 in 40,000 newborns.

Family References and Resources
Clinician References
What is Analyzed?
  • Full gene sequencing
Affected Systems



Carrier Rates
Detection Rate
Carrier Frequency
French Canadian > 99% 1 in 23
General Population > 99% 1 in 500


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