Inherited Isolated Dystonia in Children

Isolated dystonia refers to a clinical and genetic heterogeneous group of movement disorders causing repetitive twisting movements that inflict abnormal postures to different body parts, without evidence of other pathological findings on examination. Brain imaging results by definition normal, without detectable structural abnormalities. Most of the genes underlying isolated dystonia in children are inherited in an autosomal dominant fashion (DYT1, DYT6), often with reduced penetrance (30-60%); this can make it difficult to clearly individuate a positive family history to guide the clinician in the choice of genetic tests. In children, the typical site of onset is in the lower limbs, with a considerable proportion of cases that subsequently generalize to involve the trunk and upper limbs, while onset in the oromandibular and laryngeal regions as well as the neck are less frequently encountered and should always prompt to rule out secondary causes of dystonia. Recently, the discovery of new genes responsible for isolated, sometimes early-onset, dystonia in adults (GNAL, ANO3) has potentially widened the number of genetic causes of dystonia in children, in which a considerable number of cases still remains genetically undetermined.