A Case of Atypical Presentation of Paroxysmal Movement Disorder, Contributed to <i>PRRT2</i> Gene Variant

The <i>PRRT2</i> gene located at 16p11 encodes proline-rich transmembrane protein with the heterozygous <i>PRRT2</i> mutation being commonly reported. The most common variant found was the c.649dup.(Arg217Profs*8). Various case reviews documenting pathogenic <i>PRRT2</i> variants reported an association with paroxysmal movement disorders, including paroxysmal kinesigenic dyskinesia (PKD), benign familial infantile epilepsy, paroxysmal kinesigenic dyskinesia associated with infantile convulsions (PKD/IC), also known as infantile convulsions with choreoathetosis syndrome paroxysmal non-kinesigenic dyskinesia (PNKD), hemiplegic migraine, and exercise-induced dyskinesia. However, more recent reports have also documented mutation associated with a broader clinical picture presenting with congenital microcephaly, severe learning difficulties, and pharmacoresistant encephalopathy. We hereby report a patient who presented with paroxysmal dyskinesia, harbouring the mutation variant on <i>PRRT2</i> gene. At 5 months of age, our proband presented to emergency because of jerking movements while in a moving car. This was followed by generalized tonic-clonic seizures and kinesigenic posturing. The latter would occur tens of times per day and a specific trigger did not always prevail. The movements responded well to low-dose carbamazepine and genetic studies confirmed a mutated variant of c.649dup.(Arg217Profs*8).