The genetics of idiopathic torsion dystonia

Idiopathic torsion dystonia (ITD) is a disorder of the central nervous system which produces dystonic movements and postures. The spectrum of severity is wide, including severe generalised dystonia (formerly termed dystonia musculorum deformans), segmental dystonia, and focal dystonias such as torticollis, blepharospasm, and writer's cramp (table). No other neurological deficits occur in ITD, although some patients display a postural tremor that is clinically indistinguishable from essential tremor. Although ITD is frequently inherited, the genetics of the condition have only recently become clear after decades of controversy.