| Main clinical features
|
cause fatigue and lethargy in patients with normal mitochondrial enzyme activities in muscle
early childhood onset of proximal muscle weakness and learning disabilities; while the muscle weakness is static, most patients develop progressive extrapyramidal signs that may become disabling
laboratory studies showed increased serum creatine kinase, and muscle biopsy showed a myopathic process with diffuse variation in fiber size, increased frequency of internal and central nuclei, and clusters of regenerating fibers |