Fig. 1.

Locations of common disease causing mutations and symptoms they cause. Point mutations are represented by arrows; the “common deletion” is shown in the centre of the genome. Abbreviations: CPEO – chronic progressive external opthalmoplegia, LS – Leigh syndrome, MELAS – mitochondrial encephalopathy, lactic acidosis, stroke-like episodes, MERRF – Myoclonic epilepsy and ragged red fibres, MILS – maternally inherited Leigh syndrome, NARP – neurogenic weakness, ataxia and retinitis pigmentosa, PS – Pearson׳s syndrome.