Characteristics of the patients carrying the m.3243A>G mutation patients 1–17 with multi-organ presentation (subgroup I), patients 18–29 with isolated hearing loss (subgroup II), and asymptomatic carriers 30–34 (subgroup III).

Probands are shown in bold.GC-MS = gas chromatography–mass spectroscopy; NMDAS = Newcastle Mitochondrial Disease Adult Scale; MGCA = 3-methylglutaconic aciduria; LA = lactic aciduria; HL = hearing loss; NP = not performed; NA = normal value; QoL = quality of life; CI = cochlear implant user; IMGP = increased mineralisation of globus pallidus; MCA = minimal cerebellar atrophy; MRS = magnetic resonance spectroscopy; MRS score: 0 = negative LA, 1 = uncertain LA, 2 = positive LA, 3 = strong LA.C = cardiomyopathy; DM = diabetes mellitus; H = migraine; I = infertility; K = renal insufficiency; M = myopathy; N = peripheral neuropathy; RP = pigmentary degeneration of retina; S = stroke-like episodes; SS = short stature.No HL = normal hearing.*Stress = hearing deterioration following stressful event; Aminogly = hearing deterioration following aminoglycoside administration; Noise = hearing deterioration following noise exposure; Pancreatitis = hearing deterioration following acute pancreatitis; Pregnancy = hearing deterioration after pregnancy.