MYL6 (myosin light chain 6) is a regulatory light chain component of myosin complexes that functions as a structural constituent of muscle without calcium-binding capability. The protein plays essential roles in multiple cellular processes beyond muscle contraction. In spermatogenesis, MYL6 is critical for sperm head-tail coupling apparatus assembly, where it requires proper folding by the BAG5-HSPA8 chaperone system for normal sperm formation 1. MYL6 serves as a target for autoantibodies in microscopic polyangiitis, where anti-MYL6 antibodies disrupt actin rearrangement necessary for neutrophil extracellular trap formation, paradoxically leading to lower disease activity 2. The gene shows differential expression in various disease contexts, including non-alcoholic fatty liver disease where it correlates with inflammation and oxidative stress 3, and is associated with obesity-related asthma through shared genetic loci 4. MYL6 has emerged as a potential biomarker in cardiovascular diseases, being identified as a key diagnostic gene in ischemic cardiomyopathy 5 and sepsis 6, suggesting broader roles in immune regulation and cellular stress responses beyond its traditional cytoskeletal functions.