Table 1.
Clinical, genetic and neuro-otological assessment findings in adults with mitochondrial disease and a suspected balance disorder
| Clinical phenotype | Genetic diagnosis | Gender | Age | NMDAS score | Mitochondrial DNA mutant load | Primary neuro-otological diagnosis | Additional neuro-otological diagnoses | Patient-reported symptoms | SNHL | ||||||
| Blood | Urine | Muscle | Dizziness | Light-headed | Loss of balance | Unsteadiness | Falls | ||||||||
| MIDD | m.3243A>G MT-TL1 | F | 70 | 29 | 67 | Peripheral vestibulopathy (bilateral) | Y | Y | Bilateral | ||||||
| MIDD | m.3243A>G MT-TL1 | F | 33 | 14.5 | 27 | Peripheral vestibulopathy (unilateral) | Vestibular migraine (central) | Y | Y | Y | Bilateral | ||||
| MIDD | m.3243A>G MT-TL1 | F | 57 | 17.4 | 13 | 42 | Peripheral vestibulopathy (unilateral) | Y | Y | Bilateral | |||||
| MIDD | m.3243A>G MT-TL1 | F | 69 | 24.36 | 6 | 23 | Peripheral vestibulopathy (unilateral) | Y | Y | Y | Y | Y | Bilateral | ||
| MIDD | m.3243A>G MT-TL1 | F | 55 | 51.3 | No sample | BPPV | Y | Y | Y | Bilateral | |||||
| MIDD | m.3243A>G MT-TL1 | F | 60 | 35.4 | 19 | 45 | Peripheral vestibulopathy (bilateral) | Y | Y | Y | Y | Bilateral | |||
| MELAS | m.3243A>G MT-TL1 | F | 46 | 12.76 | 23 | 71 | Peripheral vestibulopathy (bilateral) | Y | Bilateral | ||||||
| MIDD | m.3243A>G MT-TL1 | F | 42 | 23.6 | 21 | Peripheral vestibulopathy (unilateral) | BPPV | Y | Y | Y | Bilateral | ||||
| MIDD | m.3243A>G MT-TL1 | F | 50 | 16.1 | 22 | 62 | Peripheral vestibulopathy (bilateral) | Y | Bilateral | ||||||
| MIDD | m.3243A>G MT-TL1 | F | 45 | 30.1 | 20 | Vestibular migraine (central) | Y | Y | Y | Y | Bilateral | ||||
| SNHL, RP, ataxia | m.3243A>G MT-TL1 | F | 65 | 27.84 | 14 | 63 | Peripheral vestibulopathy (unilateral) | Vestibular migraine (central) | Y | Y | Y | Y | Bilateral | ||
| SNHL | m.3243A>G MT-TL1 | F | 47 | 1.16 | 13 | Peripheral (unilateral) | Y | Bilateral | |||||||
| MIDD | m.3243A>G MT-TL1 | F | 40 | 42.92 | 10 | Peripheral vestibulopathy (unilateral) | Y | Y | Y | Y | Y | Bilateral | |||
| SNHL, RP, HCM | m.3243A>G MT-TL1 | F | 70 | 13.92 | 13 | BPPV | Y | Y | Y | Y | Bilateral | ||||
| SNHL | m.3243A>G MT-TL1 | M | 50 | 6.2 | 22 | Peripheral vestibulopathy (bilateral) | Y | Bilateral | |||||||
| MIDD | m.3243A>G MT-TL1 | M | 73 | 20.4 | 14 | 72 | Normal | Y | Y | Bilateral | |||||
| MERRF | m.8344A>G MT-TK | F | 43 | 14.5 | 60 | 97 | Peripheral vestibulopathy (bilateral) | BPPV | Y | Y | Y | Right | |||
| MERRF | m.8344A>G MT-TK | M | 58 | 24.36 | No sample | Not investigated (cerebellar) | Y | Y | Y | Normal | |||||
| MERRF | m.8344A>G MT-TK | F | 43 | 7.8 | No sample | Not investigated (cerebellar) | Y | Y | Bilateral | ||||||
| MERRF | m.8344A>G MT-TK | F | 55 | 31.31 | 75 | Not investigated (cerebellar) | Y | Y | Y | Normal | |||||
| MERRF | m.8344A>G MT-TK | F | 50 | 25.52 | No | Not investigated (cerebellar) | Y | Y | Y | Bilateral | |||||
| MERRF | m.8344A>G MT-TK | F | 69 | 60.32 | 60 | 74 | Peripheral vestibulopathy (bilateral) | Vestibulo-cerebellar (central) | Y | Y | Y | Y | Y | Normal | |
| RP, SNHL, DM | m.12258C>A MT-TS2 | F | 50 | 18.56 | 30 | Peripheral vestibulopathy (bilateral) | Y | Y | Y | Bilateral | |||||
| Multisystem, SNHL | m.8782G>A MT-ATP6 | M | 37 | 20.88 | 31 | 53 | Not investigated (cerebellar) | Y | Bilateral | ||||||
| Ataxia, neuropathy | m.9176T>C MT-ATP6 | M | 29 | 27.84 | 100 | Cerebellar (central) | Y | Y | Y | Bilateral | |||||
| HCM, SNHL, ataxia | m.1555A>G MT-RNR1 | M | 62 | 19.72 | 100 | Cerebellar (central) | BPPV | Y | Y | Left | |||||
| RP, SNHL | m.10038G>A MT-TG | F | 42 | 26.88 | 15 | 40 | 92 | Peripheral vestibulopathy (bilateral) | Y | Y | Y | Y | Y | Bilateral | |
| Leigh syndrome | m.13094T>C MT - ND5 | M | 24 | 20.88 | 38 | 61 | Cerebellar (central) | Y | Y | Normal | |||||
| CPEO, ataxia | Multiple mtDNA deletions | F | 57 | 40.6 | N/A | Peripheral vestibulopathy (unilateral) | Y | Y | Y | Y | Normal | ||||
| Multisystem, SNHL | Multiple mtDNA deletions | F | 64 | 76.56 | N/A | Normal | Y | Y | Y | Y | Y | Bilateral | |||
| Multisystem, SNHL | Multiple mtDNA deletions | M | 64 | 19.7 | N/A | Peripheral vestibulopathy (bilateral) | Y | Y | Y | Y | Bilateral | ||||
| CPEO, SNHL | Multiple mtDNA deletions | M | 27 | 36.5 | N/A | Peripheral vestibulopathy (bilateral) | Y | Y | Y | Right | |||||
| CPEO | Single mtDNA deletion | M | 63 | 16.24 | N/A | Not investigated (biomechanical) | Y | Normal | |||||||
| CPEO | Single mtDNA deletion | F | 26 | 16.24 | N/A | Vestibular migraine (central) | Y | Y | Normal | ||||||
| CPEO, ataxia | POLG | M | 60 | 31.32 | N/A | Peripheral vestibulopathy (bilateral) | Y | Y | Y | Y | Bilateral | ||||
| SNHL, EI | COX10 | F | 42 | 13.92 | N/A | Not investigated (biomechanical) | Y | Bilateral | |||||||
| CPEO | Clinicopathological | M | 44 | 9.28 | N/A | Peripheral vestibulopathy (unilateral) | Vestibular migraine (central) | Y | Y | Y | Y | Normal | |||
| SNHL, migraine, EI | Clinicopathological | M | 45 | 11.6 | N/A | Peripheral vestibulopathy (unilateral) | Y | Y | Bilateral | ||||||
| Multisystem | Clinicopathological | F | 32 | 29 | N/A | Normal | Y | Y | Y | Normal | |||||
| SNHL, DM, ptosis | Clinicopathological | F | 72 | 29 | N/A | Peripheral vestibulopathy (unilateral) | Y | Y | Y | Y | Y | Bilateral | |||
Mitochondrial DNA (mtDNA) mutant load describes the percentage of mutant mtDNA in the tissue analysed. Higher scores using the Newcastle Mitochondrial Disease Scale for Adults (NMDAS) indicates greater disease burden.
BPPV, benign paroxysmal positional vertigo; COX, cytochrome c oxidase; CPEO, chronic progressive external ophthalmoplegia; DM, diabetes mellitus; EI, exercise intolerance; F, female; HCM, hypertrophic cardiomyopathy; M, male; MELAS, mitochondrial encephalopathy lactic acidosis and stroke-like episodes; MERRF, myoclonic epilepsy and red ragged fibres; MIDD, maternally inherited diabetes and deafness; RP, retinitis pigmentosa; SNHL, sensorineural hearing loss; Y, yes.