Ritchie et al [22] previously found that the risk alleles of common variants rs2200733 and rs10033464 at the 4q25 PITX2c AF locus could predict whether carriers of rare mutations in SCN5A (encoding the cardiac sodium channel), NPPA, KCNA5 (encoding potassium voltage-gated channel, shaker-related subfamily, member 5), and NKX2. 5 (encoding transcriptional factor NK2 homeobox 5) developed AF, suggesting potential interaction between common variants and rare mutation in familial AF. The gene discussed is KCNA5; the disease is atrial fibrillation.