DOCUMENT

16 | InTouch WINTER 2025 Mitochondrial Encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS syndrome), is a rare disorder that affects many of the body’s systems, particularly the brain and nervous system and muscles. Mitochondrial Encephalomyopathy, Lactic Acidosis and Stroke-like Episodes (MELAS) YOUR CONDITION IN REVIEW MELAS syndrome affects boys and girls equally and all ethnic groups equally. Onset of the condition generally occurs at a young age, with approximately 75 percent of cases, beginning before the age of 20 years and most before age 40. Stroke- like episodes and mitochondrial myopathy characterize MELAS syndrome. Mitochondrial myopathies cause muscular and neurological problems. Most people with MELAS also have a buildup of lactic acid in their bodies (a condition called lactic acidosis). This increased level of acidity in the blood can lead to vomiting, abdominal pain, extreme tiredness (fatigue), muscle weakness, and difficulty breathing. Features of MELAS The typical features of MELAS syndrome are ones that make up the name of the disorder i.e. mitochondrial encephalomyopathy (muscle problems), lactic acidosis, and stroke-like episodes, with the main symptoms being headaches and seizures. Early symptoms of MELAS may include muscle weakness and pain, recurring headaches, loss of appetite, difficulty breathing, exercise intolerance and seizures. Less commonly, people with MELAS may experience involuntary muscle spasms, impaired muscle coordination, hearing loss, heart and kidney problems, diabetes, and hormonal imbalances. The distinguishing feature in MELAS syndrome is the recurrence of stroke- like episodes. Migraines occur in the majority of affected individuals and are often severe during the acute stage of a stroke. Individuals with MELAS may also have psychiatric conditions such as depressive disorders, cognitive impairments, anxiety disorder or personality change. People with MELAS may also have episodes of confusion and hallucinations often due to a fever and/or headache. Stroke-like episodes involve temporary muscle weakness Above: Mitochondrial DNA is only inherited from the Mother. Mitochondrial Father unaffected Father affected Mother affected Mother unaffected Children affected Children unaffected