KCNQ1 and atrial fibrillation: By genetical analysis of a large Chinese family inflicted with AF, Chen and his coworkers mapped a new locus for AF to chromosome 11p15.5 and in this chromosomal region discovered the first AF-causative gene, S140G-mutant KCNQ1, which encodes an α subunit of voltage-gated potassium channel (Chen et al., 2003).