title: Benign infantile convulsion as a diagnostic clue of paroxysmal kinesigenic dyskinesia: a case series.
abstract: BACKGROUND
  Paroxysmal kinesigenic dyskinesia is characterized by sudden attacks of involuntary movements. It is often misdiagnosed clinically as psychogenic illness, which distresses the patients to a great extent. A correct diagnosis will improve the quality of life in patients with paroxysmal kinesigenic dyskinesia because treatment with low doses of anticonvulsants is effective for eliminating the clinical manifestations. Paroxysmal kinesigenic dyskinesia can occur independently of or concurrently with benign infantile convulsion. Identification of PRRT2 as the causative gene of benign infantile convulsion and paroxysmal kinesigenic dyskinesia allows genetic confirmation of the clinical diagnosis.
  
  
  METHODS
  We describe the clinical features of a Japanese family with either paroxysmal kinesigenic dyskinesia or benign infantile convulsion. A PRRT2 missense mutation (c.981C > G, p.Ile327Met) was identified in two patients with benign infantile convulsion and three patients with paroxysmal kinesigenic dyskinesia as well as in two unaffected individuals. Allowing incomplete penetrance in the mutation carriers, this mutation co-segregated completely with the phenotype. The patients with paroxysmal kinesigenic dyskinesia had been misdiagnosed with psychogenic illness for many years. They were correctly diagnosed with paroxysmal kinesigenic dyskinesia when their children visited a pediatrician for benign infantile convulsion. Treatment with carbamazepine controlled their involuntary movements completely.
  
  
  CONCLUSIONS
  Paroxysmal kinesigenic dyskinesia is a treatable movement disorder that is often misdiagnosed clinically as psychogenic illness. It is important to note that two clinically distinct disorders, benign infantile convulsion and paroxysmal kinesigenic dyskinesia, are allelic conditions caused by PRRT2 mutations. Paroxysmal kinesigenic dyskinesia should be suspected in families with a child with benign infantile convulsion.
authors.forename: Naoya
authors.initials: N
authors.lastname: Matsumoto
authors.affiliation: Department of Pediatrics, Asahikawa Medical University, 2-1-1-1 Midorigaoka-Higashi, Asahikawa, Hokkaido 078-8510, Japan. satoru5p@asahikawa-med.ac.jp.
authors.forename: Satoru
authors.initials: S
authors.lastname: Takahashi
authors.forename: Akie
authors.initials: A
authors.lastname: Okayama
authors.forename: Akiko
authors.initials: A
authors.lastname: Araki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Azuma
mesh_terms: D017668:Age of Onset; D044466:Asian People / Q000235:genetics; D002648:Child; D002675:Child, Preschool; D020820:Dyskinesias / Q000235:genetics*; D020936:Epilepsy, Benign Neonatal / Q000235:genetics*; D005260:Female; D006579:Heterozygote; D006801:Humans; D007564:Japan; D008297:Male; D008565:Membrane Proteins / Q000235:genetics; D020125:Mutation, Missense / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000235:genetics; D010375:Pedigree; D012640:Seizures / Q000235:genetics*; D055815:Young Adult
chemical_list: D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; C569370:PRRT2 protein, human