Mitochondrial myopathy and sideroblastic anemia belongs to the heterogeneous family of metabolic myopathies. It is characterised by progressive exercise intolerance manifesting in childhood, onset of sideroblastic anaemia around adolescence, lactic acidaemia, and mitochondrial myopathy.

Distance between nasal base and midline upper lip vermilion border more than 2 SD above the mean. Alternatively, an apparently increased distance between nasal base and midline upper lip vermilion border.