A case of a pathological variant of the PRRT2 gene in twins with paroxysmal kinesiogenic dyskinesia

Paroxysmal dyskinesia is a clinically and etiologically polymorphic group of diseases, the main clinical manifestation of which is transient attacks of extrapyramidal movements, with different conditions of occurrence. Paroxysmal kinesigenic dyskinesia belongs to the group of primary dyskinesias, which also includes paroxysmal non-kinesigenic dyskinesia and exercise-induced paroxysmal dyskinesia. The most common cause of paroxysmal kinesiogenic dyskinesia is mutations in the PRRT2 gene; in cases of non-kinesiogenic dyskinesia, a mutation in the MR1 gene is detected. The diagnosis of primary dyskinesias causes significant difficulty for clinicians due to the rarity of occurrence, as well as the large spectrum of conditions occurring with paroxysmal motor disorders in childhood. The article describes the clinical observation of 16-year-old twin brothers with transient attacks of dystonic, choreic and ballistic hyperkinesis that suddenly arose during movement. Patients were treated for tics and epilepsy for 12 years. Taking into account the clinical picture — transient attacks of hyperkinesis, their connection with movement, as well as data from video-electroencephalographic monitoring, a diagnosis of paroxysmal kinesiogenic dyskinesia was established, which in a further diagnostic search was confirmed by targeted sequencing of the pathological variant of the PRRT2 gene previously described in patients with kinesiogenic dyskinesia. The administration of carbamazepine, which is the drug of choice in the treatment of this category of patients, has achieved significant control over hyperkinesis in twins. Thus, molecular genetic diagnosis helps confirm the diagnosis of paroxysmal dyskinesias, but careful analysis of the clinical picture, considering the provoking factor, remains the basis of diagnosis.