SUCLG1-related mitochondrial DNA depletion syndrome

SUCLG1-related mitochondrial DNA (mtDNA) depletion syndrome is an inherited disorder that affects the early development of the brain. Signs and symptoms typically appear soon after birth. Most affected children develop severe brain dysfunction and muscle weakness (encephalomyopathy). Infants with SUCLG1-related mtDNA depletion syndrome often have weak muscle tone (hypotonia). They typically have difficulty eating and may require a feeding tube. Additional features may include liver abnormalities and thickening of the heart muscle (hypertrophic cardiomyopathy). In affected individuals, a substance called methylmalonic acid typically builds up in the blood and urine. 

People with SUCLG1-related mtDNA depletion syndrome can have serious health complications, which result in a shortened lifespan. Individuals with SUCLG1-related mtDNA depletion syndrome typically do not survive past childhood. 

Some infants with SUCLG1-related mtDNA depletion syndrome develop a toxic buildup of acids in the body in the first few days of life. This form of the disorder is called fatal infantile lactic acidosis. Infants with fatal infantile lactic acidosis typically only survive for a few days after birth.