Overview
Congenital lactic acidosis, Saguenay-Lac-Saint-Jean type — also known as LSFC (Leigh Syndrome French Canadian type) or cytochrome c oxidase deficiency, French Canadian type — is a rare inherited metabolic disease that affects how the body produces energy. It is caused by a problem in the mitochondria, the tiny structures inside cells that act like power plants. When the mitochondria do not work properly, the body cannot make enough energy and builds up too much lactic acid in the blood, which is toxic at high levels. This condition mainly affects the brain, liver, and muscles. Babies born with LSFC may appear relatively stable at first but are at serious risk of sudden 'metabolic crises' — episodes where lactic acid spikes dangerously high, often triggered by illness or infection. During these crises, children can become very sick very quickly. Between crises, many children have some degree of intellectual disability, low muscle tone, and developmental delays. The liver is also commonly affected. There is currently no cure for LSFC. Treatment focuses on managing symptoms, preventing crises, and supporting development. A special diet and careful monitoring during illnesses are key parts of care. Early diagnosis and close medical follow-up can help reduce the risk of life-threatening episodes and improve quality of life.
Also known as:
Key symptoms:
Buildup of lactic acid in the blood (lactic acidosis)Low muscle tone (floppy muscles)Intellectual disability or developmental delaysLiver problems (enlarged liver or liver dysfunction)Poor feeding in infancySlow growthBreathing difficulties during crisesSudden life-threatening metabolic crises triggered by illnessNeurological deterioration over timeAbnormal brain findings on MRI (similar to Leigh syndrome)Fatigue and low energy
Clinical phenotype terms (45)— hover any for plain English
Autosomal recessive
Passed on when both parents carry the same gene change; often skips generations
Neonatal
Begins at or shortly after birth (first 4 weeks)
Treatments
No FDA-approved treatments are currently listed for Congenital lactic acidosis, Saguenay-Lac-Saint-Jean type.
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Specialists
View all specialists →No specialists are currently listed for Congenital lactic acidosis, Saguenay-Lac-Saint-Jean type.
Treatment Centers
8 centersBaylor College of Medicine Rare Disease Center ↗
Baylor College of Medicine
📍 Houston, TX
🏥 NORDStanford Medicine Rare Disease Center ↗
Stanford Medicine
📍 Stanford, CA
🔬 UDNNIH Clinical Center Undiagnosed Diseases Program ↗
National Institutes of Health
📍 Bethesda, MD
🔬 UDNUCLA UDN Clinical Site ↗
UCLA Health
📍 Los Angeles, CA
🔬 UDNBaylor College of Medicine UDN Clinical Site ↗
Baylor College of Medicine
📍 Houston, TX
🔬 UDNHarvard/MGH UDN Clinical Site ↗
Massachusetts General Hospital
📍 Boston, MA
🏥 NORDMayo Clinic Center for Individualized Medicine ↗
Mayo Clinic
📍 Rochester, MN
👤 Mayo Clinic Center for Individualized Medicine
🏥 NORDUCLA Rare Disease Day Program ↗
UCLA Health
📍 Los Angeles, CA
Travel Grants
No travel grants are currently matched to Congenital lactic acidosis, Saguenay-Lac-Saint-Jean type.
Community
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Caregiver Resources
NORD Caregiver Resources
Support, advocacy, and financial assistance for caregivers of rare disease patients.
Mental Health Support
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Family & Caregiver Grants
Financial assistance programs specifically for caregivers of rare disease patients.
Social Security Disability
Learn how rare disease patients may qualify for SSDI/SSI benefits.
Questions for your doctor
Bring these to your next appointment
- Q1.What is our emergency plan if my child gets sick or develops a fever?,What dietary guidelines should we follow, and do we need to see a metabolic dietitian?,How often should my child have blood tests to monitor lactic acid and liver function?,Are there any clinical trials or research studies we should know about?,What therapies (physical, occupational, speech) does my child need, and how do we access them?,Should other family members be tested to see if they are carriers?,What signs should prompt us to go directly to the emergency room?
Common questions about Congenital lactic acidosis, Saguenay-Lac-Saint-Jean type
What is Congenital lactic acidosis, Saguenay-Lac-Saint-Jean type?
Congenital lactic acidosis, Saguenay-Lac-Saint-Jean type — also known as LSFC (Leigh Syndrome French Canadian type) or cytochrome c oxidase deficiency, French Canadian type — is a rare inherited metabolic disease that affects how the body produces energy. It is caused by a problem in the mitochondria, the tiny structures inside cells that act like power plants. When the mitochondria do not work properly, the body cannot make enough energy and builds up too much lactic acid in the blood, which is toxic at high levels. This condition mainly affects the brain, liver, and muscles. Babies born wit
How is Congenital lactic acidosis, Saguenay-Lac-Saint-Jean type inherited?
Congenital lactic acidosis, Saguenay-Lac-Saint-Jean type follows a autosomal recessive inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Congenital lactic acidosis, Saguenay-Lac-Saint-Jean type typically begin?
Typical onset of Congenital lactic acidosis, Saguenay-Lac-Saint-Jean type is neonatal. Age of onset can vary across affected individuals.