Congenital lactic acidosis is one of the most common recessive genetic disorders in some regions of Québec:

  • Saguenay–Lac-Saint-Jean
  • Charlevoix
  • Haute-Côte-Nord.

Congenital lactic acidosis is a disease caused by an enzyme deficiency, cytochrome c oxidase. This enzyme produces the energy that the body needs to function properly. This enzyme deficiency may affect the liver, in particular.

Nearly 85% of the children with congenital lactic acidosis die before the age of 5 years. To date, a few individuals have reached the ages of 20 to 30 years, but they have limited autonomy.


Children with congenital lactic acidosis exhibit the following symptoms:

  • poor muscle tone: the child’s body is more flaccid than normal.
  • delayed motor development: for example, the child sits and walks later than children of the same age
  • failure to thrive (poor growth)
  • lack of energy to grow, ward off infections, digest food and cope with stressful life events
  • mild cognitive delay: for example, the child says their first words around the age of 4 years and must be enrolled in special education classes.


There is currently no treatment to cure congenital lactic acidosis. Early treatment for infections and a special diet help improve the quality of life of children with this disorder.

Affected children are cared for by teams of professionals in the health and social services system.


Over the years, congenital lactic acidosis can lead to serious complications. These occur especially in the case of infections. In fact, the enzyme deficiency prevents the child’s body from producing enough energy to ward off infections. The child may then experience a lactic acidosis crisis (their blood becomes too acidic), which can very quickly lead to death.


Congenital lactic acidosis is a recessive genetic disorder.

To find out more, see the page Transmission d’une maladie héréditaire récessive.

Protection and prevention

It is impossible to prevent congenital lactic acidosis in newborns who have received a copy of a defective gene from each of their two parents. However, the defective gene responsible for this disorder can be detected through a simple, quick and inexpensive screening test.

The Ministère de la Santé et des Services sociaux and the Centre intégré universitaire de santé et de services sociaux (CIUSSS) du Saguenay–Lac-Saint-Jean offer tests to detect the carriers of this disorder.

These tests are offered to anyone who:

  • is over the age of 18 years
  • wants children
  • has at least one biological grandparent born in one of the following three regions:
    • le Saguenay–Lac-Saint-Jean,
    • Charlevoix,
    • la Haute-Côte-Nord.
    In these regions, 1 in 2100 newborns is affected with congenital lactic acidosis. Furthermore, 1 in 23 people carries the defective gene responsible for this disorder.

To learn more about carrier screening, see the page Offre de tests de porteur pour 4 maladies héréditaires récessives chez les personnes originaires des régions du Saguenay–Lac-Saint-Jean, de Charlevoix et de la Haute-Côte-Nord.

Help and resources

To get help or information on congenital lactic acidosis or advice on delaying or preventing lactic acidosis crises in your child, visit the following links:

Last update: November 21, 2022


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