Paroxysmal dyskinesia due to PRRT2 mutation in 15-year-old female patient with benign familial infantile convulsions

When the now 15-year-old patient was 6 months old, the girl suffered seizures that were classified as benign familial infantile convulsions. The seizures ended spontaneously when she was a toddler and her further cognitive and motor development was normal.

Since the age of 13, the patient has been suffering paroxysmal with episodes of truncal dystonia, choreatic movements, and brief ballistic movements when walking. These attacks are mostly exercise-induced, rarely nonexercise-induced, and last for approximately 15 seconds.

Suspecting epilepsy, the patient was admitted to our epilepsy-center for video-EEG monitoring. There we observed several attacks of dyskinesia only during day time and the simultaneous EEG showed no seizure pattern. The magnetic resonance tomography of the brain was normal. Neuropsychological testing showed deficits in working memory and speech, indicating that the frontal lobe is affected.

Treatment with carbamazepine led to a decrease in the attacks, and presently, she only has short-time dystonia in her arms or feet.

Using molecular genetic methods, the mutation c.649delC in the exon 2 of the PRRT2 gene could be detected. The phenotype linked to mutations of this recently described PRRT2 gene can be very heterogeneous and manifest as benign familial epilepsy, also with choreoathetosis, paroxysmal dyskinesia, migraine, and ataxia. If further studies confirm this assumption, this would have consequences not only for genetic counseling of patients but also in daily clinical diagnostics.