Fig. 1

a The ECG of proband. The QTc interval was prolonged: 510 ms. b Family pedigree. Seventeen individuals with their respective ages and QTc interval values (between parentheses). Squares depict male subjects; circle, female subject; open symbols, unaffected members; and solid symbol, affected member. Arrow (P) denotes proband. Her father and 2 brothers died suddenly at a young age (cross). Three family members had recurrent syncope refractory to beta-blockers and/or non-sustained ventricular tachycardia requiring an implantable cardiac defibrillator (ICD). The genetic study was carried out on 7 family members (asterisk). The novel pathogenic variant was detected in five of them that manifested the LQTS phenotype