Orphanet rare-disease nomenclature term Orphanet_2597 (Mitochondrial myopathy - lactic acidosis - deafness) can be described as follows. Mitochondrial myopathy-lactic acidosis-deafness is a type of metabolic myopathy described only in two sisters to date, presenting during childhood, and characterized clinically by growth failure, severe muscle weakness, and moderate neural deafness and biochemically by metabolic acidosis, elevated serum pyruvate concentration, hyperalaninemia and hyperalaninuria. There have been no further descriptions in the literature since 1973. Also known as: Mitochondrial myopathy - lactic acidosis - hearing loss.