Objective: Describe the most frequent abnormal movements, their association with other symptoms, and the response to treatment in 4 children with ATP1A3 gene mutations.

Background: Both dominant and de novo mutations of the ATP1A3 gene have been detected in patients affected with three different phenotypes: Childhood Alternating Hemiplegia (HAI), Sudden Onset Dystonia-Parkinsonism (DYT12) and CAPOS Syndrome. In all of them, movement disorders are cardinal signs, such as abnormal eye movements, ataxia, dystonia and choreoathetosis.

Method: Clinical and video analysis of 4 patients with ATP1A3 gene mutation, confirmed with molecular genetic study.

Results: . 4 patients (3 men / 1 woman). Age of presentation 2 months to 2 years. All patients had a homozygous mutation of the ATP1A3 gene: 2/4 c.2677 G> C (p.Gly893Arg), 1/4 2542 + 1G> C (splice donor), 1/4 c.2443 G> A ( p. Glu815Lys). All 4 patients had alternating hemiplegia; 3/4 extrapyramidal syndrome, of which all presented chorea and 2 dystonia. The episodes had a daily frequency up to once a month with a duration of 5 minutes to 7 days. The best pharmacological response to episodes of hemiplegia with abnormal movements was obtained with Flunarizine, however only one of them had complete control of the symptoms and the others only a partial response. Other associated symptoms were: 2/4 cognitive impairment (delayed global psychomotor development and intellectual disability), 2/4 epilepsy; 1 monocular nystagmus.

Conclusion: All our patients presented HAI, highlighting the presence of extrapyramidal symptoms such as chorea and dystonia, and monocular nystagmus. The recommended treatment is Flunarizine, presenting a partial response in most of our patients.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/movement-disorders-in-children-with-atp1a3-gene-mutations-a-series-of-chilean-patients/