Myotonia associated with caveolin‐3 mutation

Caveolin‐3 is a major component of the caveolae in skeletal and cardiac muscle.Mutations in the caveolin‐3 gene ( CAV3 ) lead to a spectrum of clinical phenotypes including limb‐girdle muscular dystrophy 1C, distal myopathy, rippling muscle disease, isolated hyperCKemia, and cardiomyopathy. Case Report: A 24‐year‐old man with myalgia, muscle stiffness, and fatigue has normal strength and prominent myotonic discharges in the gastrocnemius. He also has epilepsy. He harbors a heterozygous CAV3 mutation, p.V57M. He has no mutations in CLCN1 and SCN4A , and he had normal genetic testing for myotonic dystrophy type 1 and type 2. Conclusions: Mutations in CAV3 , and in particular p.V57M in CAV3 , previously reported in isolated familial hyperCKemia, can be associated with electrical myotonia. Muscle Nerve 45: 897‐900, 2012