Dopa-responsive dystonia and paroxysmal dystonic attacks associated with ATP1A3 gene variant.

An 18-year-old man had episodes of severe generalised dystonia, from aged 7 months and becoming progressively more frequent. He also had gradually developed interictal limb dystonia. He was initially diagnosed with paroxysmal kinesigenic dyskinesia but he did not improve with several medications. A levodopa trial led to levodopa-induced dyskinetic movements. However, a lower titration of 25 mg of levodopa two times per day substantially improved his motor features and quality of life. Laboratory investigations and MR scans of the brain were unremarkable. Whole-exome sequencing identified a pathogenic variant in the ATP1A3 gene. The ATP1A3-spectrum disorders include non-classical phenotypes such as paroxysmal dystonic attacks. A response to dopamine response is unusual in these disorders. This case highlights the importance of levodopa trials in early-onset dystonia cases.