iagnosis of PKD is based on its characteristic symptoms, more precisely, attacks of dystonia, athetosis, and ballism triggered by sudden voluntary[[Please confirm]] movements. Attacks typically occur several times a day and affect mainly the upper and lower limbs, and the body core is rarely affected by spasm. PKD patients do not lose consciousness during attacks, and the duration of an attack is usually short (within 1 min). Although patients do not present with well-characterized neurological symptoms, they respond well to carbamazepine. The daily frequency of attacks can reach 100 or higher, causing problems in a patient’s social life. However, the frequency of attacks decreases when patients reach adulthood. Generally, symptoms are detected by people in close contact with the patient during the patient’s childhood, and diagnosis of PKD in adulthood, in accordance with subjective symptoms, is rare. However, our questionnaire survey conducted in 2009 revealed that PKD could be misdiagnosed as a mental disease such as dissociative disorder or epileptic seizure. Some patients were treated for suspected psychogenic diseases (synonymous with dissociative disorder and with hysteria in a broad sense), suggesting the importance of accurately diagnosing PKD. Although mutations in the PRRT2 gene have been revealed as the main cause of PKD, a subset of patients lacks such mutations. Furthermore, the PRRT2 gene is of particular interest since its mutation causes various neurological disorders. We aim to study the clinical symptoms and genetic functions in PKD patients in order to develop a radical cure for the disease.