The spectrum of movement disorders in young children with ARX-related epilepsy-dyskinesia syndrome.

Children with developmental and epileptic encephalopathies often present with co-occurring dyskinesias. Pathogenic variants in ARX cause a pleomorphic syndrome that includes infantile epilepsy with a variety of movement disorders ranging from focal hand dystonia to generalized dystonia with frequent status dystonicus. In this report, we present three patients with severe movement disorders as part of ARX-associated epilepsy-dyskinesia syndrome, including a patient with a novel pathogenic missense variant (p.R371G). These cases illustrate diagnostic and management challenges of ARX-related disorder and shed light on broader challenges concerning epilepsy-dyskinesia syndromes.