LAUSR

A 43-year-old man described adolescence-onset abnormal muscle contractions. On examination, there was hypertrophy (figure) with normal power of thigh muscles but mild weakness of distal leg muscles (Medical Research Council grade 4+/5). Muscle percussion and stretching induced electrically silent slow rolling muscle contractions (video 1). He had mildly elevated creatine kinase (600 U/L). Family history was consistent with autosomal dominant rippling muscle disease.1 A heterozygous variant was documented in coding exons of the caveolin 3 gene (CAV c. 83A>T;p.Asp28Val).