Roselle Gélinas1, Nabil El Khoury1, Marie-A Chaix1, Claudine Beauchamp1, Azadeh Alikashani1, Nathalie Ethier1, Gabrielle Boucher1, Louis Villeneuve1, Laura Robb1, Frédéric Latour1, Blandine Mondesert1, Lena Rivard1, Philippe Goyette1, Mario Talajic1, Céline Fiset2, John David Rioux2. 1. From the Research Center (R.G., N.E.K., M.-A.C., C.B., A.A., N.E., G.B., L.V., L.R., F.L., B.M., L.R., P.G., M.T., C.F., J.D.R.) and Cardiovascular Genetics Center (L. Robb, L. Rivard, M.T.), Montreal Heart Institute, Quebec, Canada; and Department of Medicine (R.G., M.-A.C., B.M., L.R., M.T., J.D.R.) and Faculty of Pharmacy (N.E.K., C.F.), Université de Montréal, Quebec, Canada. 2. From the Research Center (R.G., N.E.K., M.-A.C., C.B., A.A., N.E., G.B., L.V., L.R., F.L., B.M., L.R., P.G., M.T., C.F., J.D.R.) and Cardiovascular Genetics Center (L. Robb, L. Rivard, M.T.), Montreal Heart Institute, Quebec, Canada; and Department of Medicine (R.G., M.-A.C., B.M., L.R., M.T., J.D.R.) and Faculty of Pharmacy (N.E.K., C.F.), Université de Montréal, Quebec, Canada. john.david.rioux@umontreal.ca celine.fiset@umontreal.ca.
Abstract
BACKGROUND: Long-QT syndrome is a potentially fatal condition for which 30% of patients are without a genetically confirmed diagnosis. Rapid identification of causal mutations is thus a priority to avoid at-risk situations that can lead to fatal cardiac events. Massively parallel sequencing technologies are useful for the identification of sequence variants; however, electrophysiological testing of newly identified variants is crucial to demonstrate causality. Long-QT syndrome could, therefore, benefit from having a standardized platform for functional characterization of candidate variants in the physiological context of human cardiomyocytes. METHODS AND RESULTS: Using a variant in Kir2.1 (Gly52Val) revealed by whole-exome sequencing in a patient presenting with symptoms of long-QT syndrome as a proof of principle, we demonstrated that commercially available human induced pluripotent stem cell-derived cardiomyocytes are a powerful model for screening variants involved in genetic cardiac diseases. Immunohistochemistry experiments and whole-cell current recordings in human embryonic kidney cells expressing the wild-type or the mutant Kir2.1 demonstrated that Kir2.1-52V alters channel cellular trafficking and fails to form a functional channel. Using human induced pluripotent stem cell-derived cardiomyocytes, we not only confirmed these results but also further demonstrated that Kir2.1-52V is associated with a dramatic prolongation of action potential duration with evidence of arrhythmic activity, parameters which could not have been studied using human embryonic kidney cells. CONCLUSIONS: Our study confirms the pathogenicity of Kir2.1-52V in 1 patient with long-QT syndrome and also supports the use of isogenic human induced pluripotent stem cell-derived cardiomyocytes as a physiologically relevant model for the screening of variants of unknown function.
BACKGROUND:Long-QT syndrome is a potentially fatal condition for which 30% of patients are without a genetically confirmed diagnosis. Rapid identification of causal mutations is thus a priority to avoid at-risk situations that can lead to fatal cardiac events. Massively parallel sequencing technologies are useful for the identification of sequence variants; however, electrophysiological testing of newly identified variants is crucial to demonstrate causality. Long-QT syndrome could, therefore, benefit from having a standardized platform for functional characterization of candidate variants in the physiological context of human cardiomyocytes. METHODS AND RESULTS: Using a variant in Kir2.1 (Gly52Val) revealed by whole-exome sequencing in a patient presenting with symptoms of long-QT syndrome as a proof of principle, we demonstrated that commercially available human induced pluripotent stem cell-derived cardiomyocytes are a powerful model for screening variants involved in genetic cardiac diseases. Immunohistochemistry experiments and whole-cell current recordings in humanembryonic kidney cells expressing the wild-type or the mutant Kir2.1 demonstrated that Kir2.1-52V alters channel cellular trafficking and fails to form a functional channel. Using human induced pluripotent stem cell-derived cardiomyocytes, we not only confirmed these results but also further demonstrated that Kir2.1-52V is associated with a dramatic prolongation of action potential duration with evidence of arrhythmic activity, parameters which could not have been studied using humanembryonic kidney cells. CONCLUSIONS: Our study confirms the pathogenicity of Kir2.1-52V in 1 patient with long-QT syndrome and also supports the use of isogenic human induced pluripotent stem cell-derived cardiomyocytes as a physiologically relevant model for the screening of variants of unknown function.
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