en Molecular Genetics & Genomics Molecular Genetics & Genomics مقاله کوتاه Short Communication <strong>Background: </strong>Long QT syndrome (LQTS) is characterized by the prolongation of QT interval, which results in syncope and sudden cardiac death in young people. <em>KCNQ1</em> is the most common gene responsible for this syndrome. <strong>Methods: </strong>Molecular investigation was performed by DNA Sanger sequencing in Iranian families with a history of syncope. <em>In silico </em>examinations were performed for predicting the pathogenicity of the novel variant. <strong>Results: </strong>A novel homozygous <em>KCNQ1</em> frameshift mutation, c.1426_1429delATGC (M476Pfs*4), was identified, and then the current literatures of five patients were reviewed regarding the LQTS.<strong> Conclusion: </strong>The novel frameshift mutation has been reported for the first time among the Iranian population. Our finding along with the case series study of LQTS patients illustrates the importance of genetic and case series in precise detection of the frequency of LQTS carriers. Jervell-Lange‐Nielsen syndrome, KCNQ1, Long QT syndrome, Romano-Ward syndrome 228 234 http://ibj.pasteur.ac.ir/browse.php?a_code=A-10-1-761&slc_lang=en&sid=1 Azam Amirian 0000-0002-4313-2113 No Department of Molecular Medicine, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran Zahra Zafari 0000-0003-4954-9320 No Department of Molecular Medicine, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran Morteza Karimipoor 0000-0002-2406-5963 No Department of Molecular Medicine, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran Alireza Kordafshari 0000-0002-4302-8084 No Department of Molecular Medicine, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran Mohammad Dalili 0000-0000-0000-0000 No Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical, and Research Center, Iran University of Medical Sciences, Tehran, Iran Siamak Saber 0000-0000-0000-0000 No Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical, and Research Center, Iran University of Medical Sciences, Tehran, Iran Amir Farjam Fazelifar 0000-0000-0000-0000 No Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical, and Research Center, Iran University of Medical Sciences, Tehran, Iran Sirous Zeinali 0000-0002-9516-9954 Yes Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical, and Research Center, Iran University of Medical Sciences, Tehran, Iran