title: Selective acquired long QT syndrome (saLQTS) upon risperidone treatment.
abstract: BACKGROUND
  Numerous structurally unrelated drugs, including antipsychotics, can prolong QT interval and trigger the acquired long QT syndrome (aLQTS). All of them are thought to act at the level of KCNH2, a subunit of the potassium channel. Although the QT-prolonging drugs are proscribed in the subjects with aLQTS, the individual response to diverse QT-prolonging drugs may vary substantially.
  
  
  METHODS
  We report here a case of aLQTS in response to small doses of risperidone that was confirmed at three independent drug challenges in the absence of other QT-prolonging drugs. On the other hand, the patient did not respond with QT prolongation to some other antipsychotics. In particular, the administration of clozapine, known to be associated with higher QT-prolongation risk than risperidone, had no effect on QT-length. A detailed genetic analysis revealed no mutations or polymorphisms in KCNH2, KCNE1, KCNE2, SCN5A and KCNQ1 genes.
  
  
  CONCLUSIONS
  Our observation suggests that some patients may display a selective aLQTS to a single antipsychotic, without a potassium channel-related genetic substrate. Contrasting with the idea of a common target of the aLQTS-triggerring drugs, our data suggests existence of an alternative target protein, which unlike the KCNH2 would be drug-selective.
authors.affiliation: Division of General Psychiatry, University Hospitals of Geneva and Faculty of Medicine of the University of Geneva, 1202 Geneva, Switzerland. maciej.lazarczyk@hcuge.ch
authors.forename: Maciej Jakub
authors.initials: MJ
authors.lastname: Lazarczyk
authors.forename: Zahir A
authors.initials: ZA
authors.lastname: Bhuiyan
authors.forename: Nicolas
authors.initials: N
authors.lastname: Perrin
authors.forename: Panteleimon
authors.initials: P
authors.lastname: Giannakopoulos
mesh_terms: D000328:Adult; D014150:Antipsychotic Agents / Q000009:adverse effects*; D003024:Clozapine / Q000009:adverse effects; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008133:Long QT Syndrome / Q000209:etiology*; D015221:Potassium Channels / Q000187:drug effects* / Q000235:genetics; D018967:Risperidone / Q000009:adverse effects*; D012559:Schizophrenia / Q000188:drug therapy* / Q000235:genetics
chemical_list: D014150:Antipsychotic Agents; D015221:Potassium Channels; D003024:Clozapine; D018967:Risperidone