Family of Case 2 and 3 (Fig. 2A-B): The proband (case 2) and her mother (case 3, II-3) were diagnosed with LQTS-LVHT, while the younger sister of the proband (III-3) who carries the same mutation KCNH2 p.T273M was diagnosed with LQTS only (QTc = 614ms). This evidence concerns the gene KCNH2 and familial long QT syndrome.