Kv1.5 channelopathy due to KCNA5 loss-of-function mutation causes human atrial fibrillation.
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Olson TM, Alekseev AE, Liu XK, Park S, Zingman LV, Bienengraeber M, Sattiraju S, Ballew JD, Jahangir A, Terzic A
Kv1.5 channelopathy due to KCNA5 loss-of-function mutation causes human atrial fibrillation.
Hum Mol Genet. 2006 Jul 15;15(14):2185-91. Epub 2006 Jun 13.
- PubMed ID
- 16772329 [ View in PubMed]
- Abstract
Atrial fibrillation is a rhythm disorder characterized by chaotic electrical activity of cardiac atria. Predisposing to stroke and heart failure, this common condition is increasingly recognized as a heritable disorder. To identify genetic defects conferring disease susceptibility, patients with idiopathic atrial fibrillation, lacking traditional risk factors, were evaluated. Genomic DNA scanning revealed a nonsense mutation in KCNA5 that encodes Kv1.5, a voltage-gated potassium channel expressed in human atria. The heterozygous E375X mutation, present in a familial case of atrial fibrillation and absent in 540 unrelated control individuals, introduced a premature stop codon disrupting the Kv1.5 channel protein. The truncation eliminated the S4-S6 voltage sensor, pore region and C-terminus, preserving the N-terminus and S1-S3 transmembrane domains that secure tetrameric subunit assembly. Heterologously expressed recombinant E375X mutant failed to generate the ultrarapid delayed rectifier current I(Kur) vital for atrial repolarization and exerted a dominant-negative effect on wild-type current. Loss of channel function translated into action potential prolongation and early after-depolarization in human atrial myocytes, increasing vulnerability to stress-provoked triggered activity. The pathogenic link between compromised Kv1.5 function and susceptibility to atrial fibrillation was verified, at the organism level, in a murine model. Rescue of the genetic defect was achieved by aminoglycoside-induced translational read-through of the E375X premature stop codon, restoring channel function. This first report of Kv1.5 loss-of-function channelopathy establishes KCNA5 mutation as a novel risk factor for repolarization deficiency and atrial fibrillation.