PITX2 and atrial fibrillation: These SNPs are located within introns of the ENPEP gene, which is proximal on chromosome 4 to the PITX2 gene; while the AF associated SNPs are distal to PITX2. These seven SNPs are all in LD with each other and thus represent one haplotype block (r2 from 0.292 to 1, Table 10).