A female patient with a hot spot mutation of PRRT2 gene suffering from several types of epileptic seizures in infancy.

Benign familial infantile epilepsy (BFIE) is characterized by non-febrile focal seizures, which sometimes evolve to secondarily generalized seizures and are usually resolved in the second year. Proline-rich transmembrane protein 2 (PRRT2) is confirmed as the major cause of BFIE, familial paroxysmal kinesigeneic dystonia (PKD) and infantile convulsions and choreoathetosis (ICCA) syndrome. We examined a female patient with a hot spot mutation of PRRT2 gene. She had recurrent tonic seizures when she was three months old. The seizures were controlled by several kinds of anticonvulsants. Then, she had several times of focal seizures daily at nine months old. However, the seizures were stopped by small amounts of carbamazepine. Later, when she was two years old, she experienced frequent motor seizures characterized by truncal flexion and swaying the body with partially disturbed consciousness. Her father also had the same PRRT2 gene mutation and non-febrile seizures in infancy. The patient had mild to moderate mental retardation, whereas her father was mentally normal. Therefore, the patient revealed a quiet different phenotype from that of her father as a carrier of the same PRRT2 gene mutation. We speculate that the PRRT2 mutation had caused the BFIE-like seizures both in the patient and her father, whereas other unknown genetic factors specific for the patient might be associated with the atypical seizures observed only in her.