We deployed pVAAST16,17, the pedigree-enabled version of the disease-gene finder VAAST18–21, on whole-exome sequencing (WES) data from 5 members of the family with young-onset AF and identified the cardiac potassium channel gene KCNQ1 as the top candidate gene, driven by a damaging genetic variant c.692 G > A (NM_000218.2) encoding a missense substitution R231H (rs199472709, 11-2593251-G > A on GRCh37, frequency 3.19E-5 in gnomAD v2 all genomes, absent from gnomAD v2 exomes and gnomAD v3; Supplementary Methods). Here, KCNA3 is linked to atrial fibrillation.