Circulation: Cardiovascular Genetics HCG Spectrum and Prevalence of <I>CALM1-</I>, <I>CALM2-</I>, and <I>CALM3-</I>Encoded Calmodulin (CaM) Variants in Long QT Syndrome (LQTS) and Functional Characterization of a Novel LQTS-Associated CaM Missense Variant, E141G Calmodulin and LQTS CIRCCVG/2015/001323 CIRCCVG/2015/001323 10.1161/CIRCGENETICS.115.001323 9 04/19/16 2 Sine Kristina 617-542-5100 617-542-6539 MacRae, Calum Harvard Medical School/BWH Prof. Michael J Ackerman ackerman.michael@mayo.edu Prof. Mayo Clinic 200 First Street SW Rochester Minnesota 55905 UNITED STATES 507-284-8900 507-284-3757 17121 Nicole J Boczek Mayo Clinic boczek.nicole@mayo.edu 107212 Nieves Gomez-Hurtado Vanderbilt nieves.gomez-hurtado@vanderbilt.edu 264170 Dan Ye Mayo Clinic ye.dan@mayo.edu 95459 Melissa Calvert Mayo Clinic calvert.melissa@mayo.edu 312045 David Tester Mayo Clinic tester.david@mayo.edu 95460 Dmytro Kryshtal Vanderbilt University Medical Center dmytro.o.kryshtal@Vanderbilt.Edu 264171 Hyun-Seok Hwang Vanderbilt University hyun.seok.hwang@vanderbilt.edu 86028 Christopher Johnson Vanderbilt University cn.johnson@vanderbilt.edu 104777 Walter J. Chazin Vanderbilt University walter.chazin@vanderbilt.edu 104795 Christina Gale Loporcaro Mayo Clinic Loporcaro.Christina@mayo.edu 264173 Maully J Shah The Childrens Hospital of Philadelphia shahm@email.chop.edu 61825 Andrew Papez Phoenix Children's Hospital apapez@yahoo.com 157045 Yung Lau University of Alabama at Birmingham ylau@uab.edu 131759 Ronald Kanter Miami Childrens Hospital rkanter@mch.com 212787 Bjorn C. Knollmann Vanderbilt University School of Medicine bjorn.knollmann@vanderbilt.edu 26174 Michael J Ackerman Mayo Clinic ackerman.michael@mayo.edu 17121 11/20/2015 11/20/2015 02/02/2016 03/04/2016 03/11/2016 04/19/2016 Original Article <P><B><I>Background</I></B>—Calmodulin (CaM) is encoded by three genes, <I>CALM1</I>, <I>CALM2</I>, and <I>CALM3</I>, all of which harbor pathogenic variants linked to long QT syndrome (LQTS) with early and severe expressivity. These LQTS-causative variants reduce CaM affinity to Ca<sup>2+</sup> and alter the properties of the cardiac L-type calcium channel (Ca<sub>V</sub>1.2). CaM also modulates Na<sub>V</sub>1.5 and the ryanodine receptor, RyR2. All of these interactions may play a role in disease pathogenesis. Here, we determine the spectrum and prevalence of pathogenic CaM variants in a cohort of genetically elusive LQTS, and functionally characterize the novel variants. </P><P><B><I>Methods and Results</I></B>—Thirty-nine genetically elusive LQTS cases underwent whole exome sequencing to identify CaM variants. Non-synonymous CaM variants were overrepresented significantly in this heretofore LQTS cohort (15.4%) compared to exome aggregation consortium (0.04%; p<0.0001). When the clinical sequelae of these 6 CaM-positive cases was compared to the 33 CaM-negative cases, CaM-positive cases had a more severe phenotype with an average age of onset of 8 months, an average QTc of 679 ms, and a high prevalence of cardiac arrest. Functional characterization of one novel variant, E141G-CaM, revealed an 11-fold reduction in Ca<sup>2+</sup> binding affinity and a functionally-dominant loss of inactivation in Ca<sub>V</sub>1.2, mild accentuation in Na<sub>V</sub>1.5 late current, but no effect on intracellular RyR2-mediated calcium release. </P><P><B><I>Conclusions</I></B>—Overall, 15% of our genetically elusive LQTS cohort harbored non-synonymous variants in CaM. Genetic testing of <I>CALM1-3</I> should be pursued for individuals with LQTS, especially those with early childhood cardiac arrest, extreme QT prolongation, and a negative family history.</P> 3 0 0 6 6 no yes CircGenetics_CIRCCVG-2015-001323.xml CircGenetics_CIRCCVG-2015-001323_file1.docx
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CircGenetics_CIRCCVG-2015-001323_supp1.pdf CircGenetics_CIRCCVG-2015-001323_supp2.pdf CircGenetics_CIRCCVG-2015-001323_merge.pdf CircGenetics_CIRCCVG-2015-001323_Knollmann_26174_disclosure.pdf CircGenetics_CIRCCVG-2015-001323_Knollmann_26174_copyright.pdf CircGenetics_CIRCCVG-2015-001323_Lau_131759_disclosure.pdf CircGenetics_CIRCCVG-2015-001323_Lau_131759_copyright.pdf CircGenetics_CIRCCVG-2015-001323_Calvert_312045_disclosure.pdf CircGenetics_CIRCCVG-2015-001323_Calvert_312045_copyright.pdf CircGenetics_CIRCCVG-2015-001323_Kanter_212787_disclosure.pdf CircGenetics_CIRCCVG-2015-001323_Kanter_212787_copyright.pdf CircGenetics_CIRCCVG-2015-001323_Shah_61825_disclosure.pdf CircGenetics_CIRCCVG-2015-001323_Shah_61825_copyright.pdf CircGenetics_CIRCCVG-2015-001323_Hwang_86028_disclosure.pdf CircGenetics_CIRCCVG-2015-001323_Hwang_86028_copyright.pdf CircGenetics_CIRCCVG-2015-001323_Kryshtal_264171_disclosure.pdf CircGenetics_CIRCCVG-2015-001323_Kryshtal_264171_copyright.pdf CircGenetics_CIRCCVG-2015-001323_Papez_157045_disclosure.pdf CircGenetics_CIRCCVG-2015-001323_Papez_157045_copyright.pdf CircGenetics_CIRCCVG-2015-001323_Boczek_107212_disclosure.pdf CircGenetics_CIRCCVG-2015-001323_Boczek_107212_copyright.pdf CircGenetics_CIRCCVG-2015-001323_Ye_95459_disclosure.pdf CircGenetics_CIRCCVG-2015-001323_Ye_95459_copyright.pdf CircGenetics_CIRCCVG-2015-001323_Johnson_104777_disclosure.pdf CircGenetics_CIRCCVG-2015-001323_Johnson_104777_copyright.pdf CircGenetics_CIRCCVG-2015-001323_Chazin_104795_disclosure.pdf CircGenetics_CIRCCVG-2015-001323_Chazin_104795_copyright.pdf CircGenetics_CIRCCVG-2015-001323_Tester_95460_disclosure.pdf CircGenetics_CIRCCVG-2015-001323_Tester_95460_copyright.pdf CircGenetics_CIRCCVG-2015-001323_Gomez-Hurtado_264170_disclosure.pdf CircGenetics_CIRCCVG-2015-001323_Gomez-Hurtado_264170_copyright.pdf CircGenetics_CIRCCVG-2015-001323_Loporcaro_264173_disclosure.pdf CircGenetics_CIRCCVG-2015-001323_Loporcaro_264173_copyright.pdf CircGenetics_CIRCCVG-2015-001323_Ackerman_17121_disclosure.pdf CircGenetics_CIRCCVG-2015-001323_Ackerman_17121_copyright.pdf Bill authors $70 per pg. + $425 for 1 excess pgs. Article has supplemental material (1 PDF). Clinical perspective appear on last page of manuscript file. Drs. Boczek, Gomez-Hurtado, and Ye contributed equally as co-first authors. Please copy Dr. Knollmann (bjorn.knollmann@vanderbilt.edu) to all correspondence. Rec'd 11/20/15 Subject Codes: [10001] Arrhythmias [10032] Ion Channels/Membrane Transport [10084] Genetics ksine