Loss-of-function (LOF) variants in SCN1B, encoding (VGSC) β1 subunits, are linked to human diseases that carry a high risk of sudden death, including developmental and epileptic encephalopathy type 52 (DEE52, OMIM 617350), Brugada syndrome 5 (OMIM #612838), and atrial fibrillation, familial, 13 (OMIM #615377). The gene discussed is SCN1B; the disease is atrial fibrillation.