CAPZA1 and Reduced sperm motility: KO-CAPZA1 in mice resulted in significantly decreased sperm progressive motility (<i>p</i> < 0.001) and abnormal axonemal structure, without affecting testicular morphology or sperm count.<h4>Conclusion</h4>CAPZA1 deficiency impairs sperm motility and flagellar architecture through disrupted cytoskeletal protein regulation and redox imbalance, and represents a novel genetic contributor to asthenozoospermia.