MYOZ1 (myozenin 1) is a Z-disk protein that functions as an intracellular scaffold linking key sarcomeric proteins including alpha-actinin, telethonin, and LDB3, while serving as a negative regulator of calcineurin signaling 1. The protein plays critical roles in sarcomere organization, myofibril assembly, and skeletal muscle tissue development [GO annotations]. MYOZ1 expression is significantly regulated by genetic variation at the chromosome 10 locus; risk alleles associated with atrial fibrillation (AF) are consistently associated with decreased MYOZ1 expression in atrial tissue 234. Genome-wide association analysis identified MYOZ1 as a causative gene at this AF susceptibility locus, with the risk allele rs3740293 associated with reduced expression in both left and right atria 23. Recent evidence demonstrates that AF-associated genetic variants alter MYOZ1 expression through regulatory SNPs, potentially contributing to AF pathogenesis via effects on calcineurin signaling 4. In muscle regeneration contexts, MYOZ1 upregulation is associated with improved functional recovery 5. Conversely, mutations in MYOZ1 are infrequently found in dilated cardiomyopathy, suggesting limited direct monogenic involvement 6. MYOZ1 expression is downregulated during muscle culture and atrophy 7. These findings establish MYOZ1 as a sarcomeric scaffold protein with important roles in cardiac electrical function and muscle homeostasis.