Most notably, the chromosome 4q25 genomic locus, which exhibits the highest association with atrial fibrillation, contains enhancers that control expression of the homeodomain transcriptional factor Pitx2, a key regulator of left atrial identity and pulmonary venous myocardium that also inhibits growth of the left-sided SAN node primordium (Roselli et al., 2018). This evidence concerns the gene PITX2 and atrial fibrillation.