A rare congenital non-dystrophic mild slowly progressive proximal myopathy characterized by exercise intolerance and post-exercise myalgia without rhabdomyolysis, associated with highly organized hexagonally cross-linked tubular arrays in skeletal muscle biopsy. Additional features may include muscle atrophy (or diffuse hypotrophy), myalgia with or without muscular weakness, paresis of truncal and limb-girdle musculature, minimal ptosis, lumbar hyperlordosis, decreased deep tendon reflexes, contractures and pes equinovarus. [from
SNOMEDCT_US]