Mitochondrial Dna Depletion Syndrome, Encephalomyopathic Form With Methylmalonic Aciduria

Mitochondrial DNA depletion syndrome, encephalomyopathic form with methylmalonic aciduria (MTDPS9) affects the brain, nervous system, and muscles. Symptoms are different from person to person. They may include muscle weakness, hearing loss, and difficulty feeding and breathing. Other symptoms may include severe low muscle tone, developmental delay, and cognitive impairment. Symptoms usually begin in early infancy and get worse over time, often leading to death in infancy. MTDPS9 is caused by genetic variants in the SUCLG1 gene (also known as the SUCLA1 gene) and is inherited in an autosomal recessive pattern. Diagnosis is based on the symptoms, clinical exam, imaging studies, and the removal of a small piece of muscle for examination (muscle biopsy). The diagnosis may also be confirmed by the results of genetic testing. Treatment is focused on managing the symptoms and providing support.