A rare genetic neuromuscular disease with characteristics of late onset of mild, progressive proximal muscle weakness, severe myalgia during and after exercise, and susceptibility to rhabdomyolysis. Intellectual disability is mild or absent. There are no abnormalities of the skin. Muscle biopsy shows focal depletion of mitochondria especially at the centre of muscle fibres, surrounded by enlarged mitochondria at the periphery. [from
SNOMEDCT_US]