MYOZ1 and atrial fibrillation: Since the expression of MYOZ1 and the SYNPO2L isoforms is inversely regulated by the AF risk alleles at this locus, we think it is likely that there is a risk haplotype consisting of two or more linked SNPs that decreases MYOZ1 expression (rs11000728) and regulates the varying expression of the four SYNPO2L isoforms.