title: Mutations in the potassium channel subunit KCNE1 are associated with early-onset familial atrial fibrillation.
abstract: BACKGROUND
  Atrial fibrillation (AF) is the most common arrhythmia. The potassium current IKs is essential for cardiac repolarization. Gain-of-function mutations in KV7.1, the pore-forming α-subunit of the IKs channel, have been associated with AF. We hypothesized that early-onset lone AF is associated with mutations in the IKs channel regulatory subunit KCNE1.
  
  
  METHODS
  In 209 unrelated early-onset lone AF patients (< 40 years) the entire coding sequence of KCNE1 was bidirectionally sequenced. We analyzed the identified KCNE1 mutants electrophysiologically in heterologous expression systems.
  
  
  RESULTS
  Two non-synonymous mutations G25V and G60D were found in KCNE1 that were not present in the control group (n = 432 alleles) and that have not previously been reported in any publicly available databases or in the exom variant server holding exom data from more than 10.000 alleles. Proband 1 (female, age 45, G25V) had onset of paroxysmal AF at the age of 39 years. Proband 2 (G60D) was diagnosed with lone AF at the age of 33 years. The patient has inherited the mutation from his mother, who also has AF. Both probands had no mutations in genes previously associated with AF. In heterologous expression systems, both mutants showed significant gain-of-function for IKs both with respect to steady-state current levels, kinetic parameters, and heart rate-dependent modulation.
  
  
  CONCLUSIONS
  Mutations in KV7.1 leading to gain-of-function of IKs current have previously been described in lone AF, yet this is the first time a mutation in the beta-subunit KCNE1 is associated with the disease. This finding further supports the hypothesis that increased potassium current enhances AF susceptibility.
authors.affiliation: The Danish National Research Foundation Centre for Cardiac Arrhythmia, Copenhagen, Denmark.
authors.forename: Morten S
authors.initials: MS
authors.lastname: Olesen
authors.forename: Bo H
authors.initials: BH
authors.lastname: Bentzen
authors.forename: Jonas B
authors.initials: JB
authors.lastname: Nielsen
authors.forename: Annette B
authors.initials: AB
authors.lastname: Steffensen
authors.forename: Jens-Peter
authors.initials: JP
authors.lastname: David
authors.forename: Javad
authors.initials: J
authors.lastname: Jabbari
authors.forename: Henrik K
authors.initials: HK
authors.lastname: Jensen
authors.forename: Stig
authors.initials: S
authors.lastname: Haunsø
authors.forename: Jesper H
authors.initials: JH
authors.lastname: Svendsen
authors.forename: Nicole
authors.initials: N
authors.lastname: Schmitt
mesh_terms: D000328:Adult; D017668:Age of Onset; D001281:Atrial Fibrillation / Q000453:epidemiology* / Q000235:genetics* / Q000503:physiopathology; D001483:Base Sequence; D015331:Cohort Studies; D004252:DNA Mutational Analysis; D003718:Denmark / Q000453:epidemiology; D004553:Electric Conductivity; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D015640:Ion Channel Gating; D007700:Kinetics; D008297:Male; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics*; D010375:Pedigree; D024642:Potassium Channels, Voltage-Gated / Q000235:genetics*; D021122:Protein Subunits / Q000235:genetics*
chemical_list: C489622:KCNE1 protein, human; D050505:Mutant Proteins; D024642:Potassium Channels, Voltage-Gated; D021122:Protein Subunits