SCN5A and atrial fibrillation: Although aggregate genetic predisposition to PR interval prolongation is associated with reduced AF risk, top PR interval prolonging alleles are associated with decreased AF risk (e.g., localized to the SCN5A/SCN10A locus; Supplementary Fig. 11) whereas others are associated with increased AF risk (e.g., localized to the TTN locus; Supplementary Fig. 11), consistent with prior reports8.