Prominent Lower-Limb Involvement in a Family with Myoclonus-Dystonia.

We report on a large family with myoclonus-dystonia resulting from an epsilon-sarcoglycan mutation, with prominent early and late lower-limb involvement. The proband's condition has evolved to include marked lower-limb dystonia and dystonic gait impairment in the fourth decade. Other family members had evidence of prominent lower-limb involvement at presentation or a more typical phenotype of axial and upper-limb myoclonus and dystonia. Prominent lower-limb involvement developing late in the disease course is an atypical feature and exemplifies the wide phenotypic heterogeneity observed in people with myoclonus-dystonia.