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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 ?-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.

SUBMITTER: Olesen MS

PROVIDER: S-EPMC3359244 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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Mutations in the potassium channel subunit KCNE1 are associated with early-onset familial atrial fibrillation.

Olesen Morten S MS Bentzen Bo H BH Nielsen Jonas B JB Steffensen Annette B AB David Jens-Peter JP Jabbari Javad J Jensen Henrik K HK Haunsø Stig S Svendsen Jesper H JH Schmitt Nicole N

BMC medical genetics 20120403

<h4>Background</h4>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.<h4>Methods</h4>In 209 unrelated early-onset lone AF patients (< 40 years) the entire coding sequence of KCNE1 was bidirectionally ...[more]

PMID: 22471742

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Project description:CONTEXT:Although the heritability of atrial fibrillation (AF) is established, the contribution of familial AF to predicting new-onset AF remains unknown. OBJECTIVE:To determine whether familial occurrence of AF is associated with new-onset AF beyond established risk factors. DESIGN, SETTING, AND PARTICIPANTS:The Framingham Heart Study, a prospective community-based cohort study started in 1948. Original and Offspring Cohort participants were aged at least 30 years, were free of AF at the baseline examination, and had at least 1 parent or sibling enrolled in the study. The 4421 participants in this analysis (mean age, 54 [SD, 13] years; 54% women) were followed up through December 31, 2007. MAIN OUTCOME MEASURES:Incremental predictive value of incorporating different features of familial AF (any familial AF, premature familial AF [onset ?65 years old], number of affected relatives, and youngest age of onset in a relative) into a risk model for new-onset AF. RESULTS:Across 11,971 examinations during the period 1968-2007, 440 participants developed AF. Familial AF occurred among 1185 participants (26.8%) and premature familial AF occurred among 351 participants (7.9%). Atrial fibrillation occurred more frequently among participants with familial AF than without familial AF (unadjusted absolute event rates of 5.8% and 3.1%, respectively). The association was not attenuated by adjustment for AF risk factors (multivariable-adjusted hazard ratio, 1.40; 95% confidence interval [CI], 1.13-1.74) or reported AF-related genetic variants. Among the different features of familial AF examined, premature familial AF was associated with improved discrimination beyond traditional risk factors to the greatest extent (traditional risk factors, C statistic, 0.842 [95% CI, 0.826-0.858]; premature familial AF, C statistic, 0.846 [95% CI, 0.831-0.862]; P = .004). Modest changes in integrated discrimination improvement were observed with premature familial AF (2.1%). Net reclassification improvement (assessed using 8-year risk thresholds of <5%, 5%-10%, and >10%) did not change significantly with premature familial AF (index statistic, 0.011; 95% CI, -0.021 to 0.042; P = .51), although categoryless net reclassification was improved (index statistic, 0.127; 95% CI, 0.064-0.189; P = .009). CONCLUSIONS:In this cohort, familial AF was associated with an increased risk of AF that was not attenuated by adjustment for AF risk factors including genetic variants. Assessment of premature familial AF was associated with a very slight increase in predictive accuracy compared with traditional risk factors.

Dataset Information

Mutations in the potassium channel subunit KCNE1 are associated with early-onset familial atrial fibrillation.

Publications

Mutations in the potassium channel subunit KCNE1 are associated with early-onset familial atrial fibrillation.

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