Sources:42NIH Rare Diseases, 32MalaCardsSee all sources NIH Rare Diseases:42 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,