Diplopia, Distal muscle weakness, Dysarthria, Dysmyelinating leukodystrophy, Flexion contracture, Generalized limb muscle atrophy, Hearing impairment, Hyperreflexia, Hypoplasia of the corpus callosum, Hyporeflexia, Hypotonia, Impaired distal proprioception, Impaired pursuit initiation and maintenance, Impaired vibration sensation in the lower limbs, Impaired visuospatial constructive cognition, Increased circulating lactate concentration, Increased CSF lactate, Intellectual disability, Leg muscle stiffness, Leukoencephalopathy, Loss of ambulation, Mental deterioration, Motor delay, Muscle weakness, Nystagmus, obsolete Difficulty walking, Optic atrophy, Peripheral axonal neuropathy, Polyneuropathy, Poor fine motor coordination, Progressive cerebellar ataxia, Progressive spasticity, Ptosis, Reduced tendon reflexes, Seizure, Skeletal muscle atrophy, Slow saccadic eye movements, Slurred speech, Spastic ataxia, Spastic/hyperactive bladder, Spasticity, Specific learning disability, Tremor, Truncal ataxia, Unsteady gait, Upper motor neuron dysfunction