After the interview, each proband was asked to participate in a family study. Probands were told that dystonia may be sometimes so mild that neither the affected subjects nor their close family and friends may be aware of symptoms; conversely, examination by an expert physician has a greater chance of identifying dystonia even in apparently asymptomatic subjects. A neurologist (D.M.) blinded to previous interviews and trained in movement disorders visited at home all first-degree relatives giving informed consent. Family members underwent complete neurological examination, including triggering maneuvers for dystonic movements or postures in asymptomatic subjects. Subjects were asked to repeatedly open and close their eyes or their mouth, look upward and downward, speak, walk, read, and perform manual tasks, including spontaneous and dictated writing. Definite dystonia was diagnosed when slow dystonic movements and abnormal postures occurred at rest or were activated by specific tasks. Blepharospasm (BSP) was defined as tonic or clonic episodes of involuntary eyelid closure associated with signs of orbicularis oculi muscle contraction, such as lowering of the brows beneath the superior orbital margin (Charcot sign). Oromandibular dystonia was diagnosed when spasms of the tongue, mandible, or floor of the mouth muscles were associated with involuntary jaw deviation, closing, or opening. Cervical dystonia was diagnosed when slow dystonic movements or abnormal neck postures were associated with head jerks. Finally, limb dystonia was diagnosed when slow dystonic movements and awkward postures developed at rest or were activated by specific tasks. Increased blinking with no evidence of Charcot sign, features suggesting so-called apraxia of eyelid opening,6 unusual tight hand gripping with writing, and isolated focal action tremor7 were not assigned a diagnosis of definite dystonia because their diagnostic value is unclear. Coexistence of postural tremor and dystonia in the same body region did not exclude the diagnosis of definite dystonia. Diagnoses made on site were confirmed through direct or videotape examination by 2 senior neurologists (A.B. and G.D.) expert in dystonia, blinded to the previously assigned diagnoses. Each affected relative was also asked about awareness of dystonia and interference of dystonia (yes or no) with at least 1 of the following activities of daily living: reading, writing, watching television, walking, shopping, performing manual tasks, housework, or outside jobs.