Clinical features and genetic analysis of paroxysmal kinesigenic dyskinesia in children

To summarize the clinical features and genetic variation spectrum of children with paroxysmal kinesigenic dyskinesia (PKD) admitted to the Children's Medical Center of Union Hospital Affiliated to Fujian Medical University and to provide references for clinical diagnosis and genetic counseling.

A retrospective analysis was conducted on the clinical data of 6 pediatric patients diagnosed with PKD in our hospital from November 2018 to August 2025. The data included medical history, triggering factors, clinical manifestations, auxiliary examinations, and treatment responses. Whole-exome sequencing (WES) was employed to detect gene mutations, followed by Sanger sequencing for verification. The pathogenicity of the identified variants was assessed according to the guidelines of the American College of Medical Genetics and Genomics (ACMG).

The study cohort included 5 males and 1 female, with an age of onset ranging from 5 to 12 years. Two cases were familial, while four were sporadic. All paroxysmal episodes were induced by sudden movement, postural change, or anxiety. The clinical manifestations included unilateral or bilateral limb posturing, tremor, athetosis, dystonia, and weakness, without impairment of consciousness. The attacks were brief (duration ≤50 s) and occurred with a frequency ranging from 1-2 per month to 5-6 per day. A history of febrile seizures was present in three patients. The magnetic resonance imaging (MRI) scan of the brain of one child showed a lacune in the right frontal lobe, and video electroencephalogram (VEEG) of another child revealed abnormal epileptic discharges during the interictal period. Genetic analysis via whole-exome sequencing (WES) identified pathogenic variants in all six patients: five harbored PRRT2 mutations (including point mutations c.649dupC, c.972delA, and c.1141delC, or exon deletions), and one had a KCNMA1 mutation (c.946G>A). Regarding treatment, four patients administered low-dose carbamazepine and two received low-dose oxcarbazepine, all of whom achieved complete or substantial control of the dyskinetic attacks.

The clinical features of pediatric PKD align with typical paroxysmal manifestations. The PRRT2 gene is the primary pathogenic gene, although cases associated with KCNMA1 mutations were also identified. Both carbamazepine and oxcarbazepine demonstrated efficacy in treating childhood PKD. Genetic testing facilitates definitive diagnosis and genetic subtyping.