SCN5A and supraventricular ectopy: While the C allele was showed to be the risk allele for PR interval (Smith et al., 2011), QRS duration (Evans et al., 2016; Swenson et al., 2019), and decreased SCN5A RNA expression in the human cardiac tissue (Evans et al., 2016), the T allele was the risk allele in supraventricular ectopy (Napier et al., 2018), PR interval (Butler et al., 2012), QT interval (Méndez-Giráldez et al., 2017) and P-wave duration (Christophersen et al., 2017).