We have mapped LQTS mutations identified as pathogenic according to ClinVar (Harrison et al., 2016) and HGMD (Stenson et al., 2012) databases onto the human KCNQ1 (Sun and Mackinnon, 2020) and hERG structures (Wang and Mackinnon, 2017), as well as a recent model of SCN5A (Kroncke et al., 2019) and the rat SCN5A homolog (Jiang et al., 2020) (Figures 9–11). Here, KCNQ1 is linked to familial long QT syndrome.