Table 2.
Clinical features of patients with MFN2 mutations.
| Mutation | Patient # | Proximal weakness UL * | Distal weakness UL * | Proximal weakness LL * | Distal weakness LL * | Cutaneous sensation UL/LL§ | Pallesthesia UL/LL§ | Proprioception UL/LL§ | Optic atrophy | Scoliosis | Intellectual disability | Restrictive lung disease/Non-invasive respiratory support | Additional symptoms |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| R94Q | 01–1 | − | +++ | + | +++ | +/+ | −/− | −/− | − | − | − | − | − |
| R104W | 02–1 | − | +++ | + | +++ | −/− | −/− | −/− | + | − | + | − | Bilateral cataracts, epilepsia partialis continua |
| 03–1 | + | + | ++ | ++ | −/− | −/+ | −/− | + | − | + | − | Lower limbs myoclonus, spastic paraparesis, dysphagia, sensorineural hearing defect | |
| 03–2 | + | +++ | +++ | +++ | −/− | −/− | −/− | − | − | + | + | Dysarthria, ataxic gait features | |
| 03–3 | ++ | +++ | ++ | +++ | −/+ | −/− | −/− | + | − | + | − | Dysarthria, lower limbs myoclonus | |
| T236M | 04–1 | − | − | + | ++ | −/− | −/− | −/− | − | − | − | − | − |
| S249C | 05–1 | − | + | + | +++ | −/− | −/− | −/− | − | − | − | − | − |
| R280H | 06–1 | − | + | + | ++ | −/− | −/− | −/− | + | − | − | − | Sensorineural hearing defect |
| 07–1 | − | ++ | − | +++ | −/− | −/− | −/− | − | − | − | − | Dysphagia, ptosis | |
| 08–1 | − | − | − | ++ | −/− | −/− | −/− | − | − | − | + | MEPs/SSEPs alteration | |
| K357E | 09–1 | + | +++ | +++ | +++ | +/+ | +/+ | +/+ | + | + | − | + | Vocal cord paresis |
| A383V | 10–1 | − | + | + | +++ | −/− | −/− | −/− | − | − | − | − | − |
| 10–2 | − | +++ | − | +++ | −/− | +/+ | −/− | − | − | − | − | − |
LL lower limbs, LMN lower motor neuron, MEP motor evoked potentials, SSEP somato-sensory evoked potentials, UL upper limbs.
*Motor weakness assessed by Medical Research Council scale (MRC): UL proximal weakness assessed by deltoids, biceps brachii and triceps, UL distal weakness assessed by first dorsal interosseus, abductor pollicis brevis and adductor digiti minimi muscles, LL proximal weakness assessed by iliopsoas, quadriceps and hamstring muscles, LL distal weakness assessed by anterior tibialis, gastrocnemius and extensor hallucis longus muscles. −: no weakness; +: slight weakness (> / = 4);++: moderate weakness (3 to 4);+++: severe weakness (< / = 3).
§Cutaneous sensation is based on pinprick examination: normal is no definite decrease compared to a normal reference point. Pallesthesia is assessed with Rydel-Seiffer tuning fork: normal is ≥ 5. Proprioception is based on joint position sensation. In the Table, cutaneous sensation, pallesthesia and proprioception are defined as normal (+) or impaired (−) in upper limbs/lower limbs.