Table 3: Treatment considerations for selected childhood-onset movement disorders.

As cohorts of individuals with monogenic movement disorders are increasingly well-described in the literature, descriptions emerge of the extent of the neurologic phenotype as well as response to specific interventions. It should be noted that most evidence along these lines is at the case series level with a few small randomized controlled trials.

Gene and corresponding condition	Description of movement disorder	Treatment considerations
TOR1A: Early-Onset Isolated Dystonia (DYT1)	Isolated dystonia typically beginning distally in middle childhood frequently progressing over months to years sparing the larynx and neck 63	Oral/injected medication is similar to that in dystonia more broadly. GPi DBS often produces sustained efficacy for refractory cases 64
GCH1: Autosomal Dominant Dopa-Responsive Dystonia (DYT5a)65	Classically with diurnally-varying childhood-onset dystonia beginning distally with gradual progression to generalized dystonia with pyramidal symptoms though an expanding recognized phenotypic spectrum	Typically dramatic and sustained response to relatively low doses of orally administered levodopa (20–30 mg/kg/day)
SGCE: Myoclonus-dystonia (DYT11)	Myoclonus frequently with focal/segmental dystonia beginning in childhood with clinical course ranging from spontaneous remission to gradual progression66	Response to many therapies has been reported including benzodiazepines, antiepileptic drugs, L-dopa, zolpidem, and VIM or GPi DBS 67
GNAO1-related movement disorder	Episodic choreoathetotic movement disorder. Early hypotonia with later dystonia is common. Frequently progressive motor and cognitive deficits 68	Hyperkinetic movements can be very treatment-resistant. Topiramate has been suggested as first-line for chorea69; cases have also reported response to tetrabenazine, GPi DBS68, or intrathecal baclofen70
GCDH: Glutaric Aciduria Type 171	Stepwise motor decline during early childhood (prior to age 3) with development of dystonia, axial hypotonia, and later rigid parkinsonism	Frequently preventable with oral carnitine supplementation early in life. However, symptoms that do arise can be very refractory with little evidence of benefit for treatments beyond baclofen (oral or intrathecal) and benzodiazepines72. Response to DBS has been discouraging to date 73
DDC: Aromatic L-amino acid decarboxylase (AADC) deficiency74	Variable degrees of (typically non-progressive) axial hypotonia with limb hypertonia; typical movement disorders include oculogyric crises, dystonia, or hypokinesia	Response to dopaminergic agents and pyridoxine have been reported, and trials are recommended, but data on efficacy is limited