title: PRRT2 phenotypes and penetrance of paroxysmal kinesigenic dyskinesia and infantile convulsions.
abstract: OBJECTIVE
  To describe the phenotypes and penetrance of paroxysmal kinesigenic dyskinesia (PKD), a movement disorder characterized by attacks of involuntary movements occurring after sudden movements, infantile convulsion and choreoathetosis (ICCA) syndrome, and benign familial infantile convulsions (BFIC), caused by PRRT2 mutations.
  
  
  METHODS
  We performed clinical and genetic studies in 3 large families with ICCA, 2 smaller families with PKD, and 4 individuals with sporadic PKD. Migraine was also present in several individuals.
  
  
  RESULTS
  We detected 3 different PRRT2 heterozygous mutations: the recurrent p.Arg217Profs*8 mutation, previously reported, was identified in 2 families with ICCA, 2 families with PKD, and one individual with sporadic PKD; one novel missense mutation (p.Ser275Phe) was detected in the remaining family with ICCA; and one novel truncating mutation (p.Arg217*) was found in one individual with sporadic PKD. In the 2 remaining individuals with sporadic PKD, PRRT2 mutations were not detected. Importantly, PRRT2 mutations did not cosegregate with febrile convulsions or with migraine. The estimated penetrance of PRRT2 mutations was 61%, if only the PKD phenotype was considered; however, if infantile convulsions were also taken into account, the penetrance was nearly complete. Considering our findings and those reported in literature, 23 PRRT2 mutations explain ∼56% of the families analyzed.
  
  
  CONCLUSIONS
  PRRT2 mutations are the major cause of PKD or ICCA, but they do not seem to be involved in the etiology of febrile convulsions and migraine. The identification of PRRT2 as a major gene for the PKD-ICCA-BFIC spectrum allows better disease classification, molecular confirmation of the clinical diagnosis, and genetic testing and counseling.
authors.affiliation: Department of Clinical Genetics, Erasmus MC, Rotterdam, the Netherlands.
authors.forename: Rianne
authors.initials: R
authors.lastname: van Vliet
authors.forename: Guido
authors.initials: G
authors.lastname: Breedveld
authors.forename: Johanneke
authors.initials: J
authors.lastname: de Rijk-van Andel
authors.forename: Eva
authors.initials: E
authors.lastname: Brilstra
authors.forename: Nienke
authors.initials: N
authors.lastname: Verbeek
authors.forename: Corien
authors.initials: C
authors.lastname: Verschuuren-Bemelmans
authors.forename: Maartje
authors.initials: M
authors.lastname: Boon
authors.forename: Johnny
authors.initials: J
authors.lastname: Samijn
authors.forename: Karin
authors.initials: K
authors.lastname: Diderich
authors.forename: Ingrid
authors.initials: I
authors.lastname: van de Laar
authors.forename: Ben
authors.initials: B
authors.lastname: Oostra
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Bonifati
authors.forename: Anneke
authors.initials: A
authors.lastname: Maat-Kievit
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D020820:Dyskinesias / Q000150:complications / Q000235:genetics*; D004421:Dystonia / Q000150:complications / Q000235:genetics*; D020936:Epilepsy, Benign Neonatal / Q000150:complications / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D008881:Migraine Disorders / Q000150:complications / Q000235:genetics; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000235:genetics*; D010375:Pedigree; D019683:Penetrance; D010641:Phenotype; D012640:Seizures / Q000150:complications / Q000235:genetics*; D003294:Seizures, Febrile / Q000150:complications / Q000235:genetics*
chemical_list: D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; C569370:PRRT2 protein, human