Dystonia refers to a group of neurological disorders characterized by abnormal involuntary and sustained twisting movements that may affect one or more sites in the body. Dystonia can be clasisfied into several sub-types, based on the genetic loci involved.
Chouery et al. (2008) studied a consanguineous Lebanese family with three affected patienst with primary focal torsion dystonia. Homozygosity mapping in the family identified a novel locus within a 20.5 Mb interval on chromosome 20. None of the 27 candidate genes tested in this region showed any causative variants.