Neurologic findings
- Neurodevelopmental regression to a vegetative state
- Cognitive disability
- Spasticity
- Hyperreflexia
- Absent speech
- Leukodystrophy of the subcortical region, cerebellum,
- Progressive loss of developmental milestones, typically beginning during early infancy (three to seven months)
- Spasticity
- Impaired speech
Muscle
- Hypotonia
- Atrophic fibers seen on biopsy
- Some abnormal aggregation of mitochondria
Ophthalmologic features
- Optic atrophy
- Loss of eye contact
- Nystagmus
- Visual impairment
Brain MRI findings
- Diffuse bilateral symmetric signal abnormality in cerebral white matter
- In some cases, signal abnormalities in the corpus callosum, internal capsule, midbrain, middle cerebellar peduncles, and cervical spinal cord
Supportive laboratory findings
- – Increased CSF glycine, glutamate, and lactate
- – Fibroblasts show decreased mitochondrial complex I and II activity
- – Mildly decreased complex IV activity
- – Decreased mtDNA levels
- – Decreased mitochondrial membrane potential
- – Decreased oxidative phosphorylation and ATP production
- Respiratory chain enzyme analysis on muscle tissue reveals deficient activity of complex II and IV