While SCN1A (Brownstein et al., 2018; Halvorsen et al., 2016) and SCN1B (Altshuler et al., 2012; Baruteau et al., 2017; Denti, n.d.; Neubauer et al., 2017) have strong prior associations with epilepsy, arrhythmia, and sudden death, and SCN4A (Männikkö et al., 2018) a recent association with sudden death, we additionally observed variants in the SCN paralogs SCN3A, SCN9A, and SCN10A that have yet to be conclusively associated with sudden death. Here, SCN4A is linked to cardiac arrhythmia.