Referenced in: none

Automatically associated channels: Kv7.1

Title: IKs Gain- and Loss-of-Function In Early-Onset Lone Atrial Fibrillation.

Authors: Annette Buur Steffensen, Lena Refsgaard, Martin Nybo Andersen, Cecilia Vallet, Amer Mujezinovic, Stig Haunsø, Jesper Hastrup Svendsen, Søren-Peter Olesen, Morten Salling Olesen, Nicole Schmitt

Journal, date & volume: J. Cardiovasc. Electrophysiol., 2015 Mar 19 , ,

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/25786344

Abstract
Atrial fibrillation (AF) is the most frequent cardiac arrhythmia. The potassium current IKs is essential for cardiac repolarization. Gain-of-function mutation in KCNQ1, the gene encoding the pore-forming α-subunit of the IKs channel (KV 7.1), was the first ion channel dysfunction to be associated with familial AF. We hypothesized that early-onset lone AF is associated with a high prevalence of mutations in KCNQ1.We bidirectionally sequenced the entire coding sequence of KCNQ1 in 209 unrelated patients with early-onset lone AF (<40 years) and investigated the identified mutations functionally in a heterologous expression system. We found 4 nonsynonymous KCNQ1 mutations (A46T, R195W, A302V, and R670K) in 4 unrelated patients (38, 31, 39, and 36 years, respectively). None of the mutations were present in the control group (n = 416 alleles). No other mutations were found in genes previously associated with AF. The mutations A46T, R195W, and A302V have previously been associated with long-QT syndrome. In line with previous reports, we found A302V to display a pronounced loss-of-function of the IKs current, while the other mutants exhibited a gain-of-function phenotype.Mutations in the IKs channel leading to gain-of-function have previously been described in familial AF, yet this is the first time a loss-of-function mutation in KCNQ1 is associated with early-onset lone AF. These findings suggest that both gain-of-function and loss-of-function of cardiac potassium currents enhance the susceptibility to AF.