Mosaic caveolin-3 expression in acquired rippling muscle disease without evidence of myasthenia gravis or acetylcholine receptor autoantibodies.

Inherited rippling muscle disease is an autosomal dominant disorder usually associated with caveolin-3 mutations. Rare cases of acquired rippling muscle disease with abnormal caveolin-3 localisation have been reported, without primary caveolin-3 mutations and in association with myasthenia gravis and acetylcholine receptor autoantibodies, or thymoma. We present three new patients with electrically-silent muscle rippling and abnormal caveolin-3 localisation, but without acetylcholine receptor autoantibodies, or clinical or electrophysiological evidence of myasthenia gravis. An autoimmune basis for rippling muscle disease is supported by spontaneous recovery and normalisation of caveolin-3 staining in one patient and alleviation of symptoms in response to plasmapheresis and immunosuppression in another. These patients expand the autoimmune rippling muscle disease phenotype, and suggest that autoantibodies to additional unidentified muscle proteins result in autoimmune rippling muscle disease.