Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Mitochondrial encephalomyopathy lactic acidosis and stroke-like episodes ?
    ### Response:
    Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) affects many parts of the body, particularly the brain and nervous system (encephalo-) and muscles (myopathy). Symptoms typically begin in childhood and may include muscle weakness and pain, recurrent headaches, loss of appetite, vomiting, and seizures.
    