DNAL1 encodes dynein axonemal light chain 1, a critical component of outer dynein arm (ODA) complexes in motile cilia and flagella 1. The protein functions as part of multisubunit axonemal ATPase complexes that generate force for ciliary motility and regulate beat frequency 1. DNAL1 specifically binds to dynein heavy chain DNAH5 and may serve in a mechanosensory feedback mechanism controlling ODA activity by tethering the outer arm dynein heavy chain to microtubules within the axoneme 1. The protein is essential for normal ciliary function in airways and for cilia-mediated nodal flow required for left-right body asymmetry determination 1. DNAL1 is expressed specifically in testis, embryonic node, respiratory epithelium, and ependyma 1. Disease-wise, DNAL1 mutations cause primary ciliary dyskinesia with respiratory symptoms and male infertility 23. The protein also plays roles in sperm flagellar assembly, where its deficiency disrupts inner dynein arms and fibrous sheath formation, leading to severe asthenozoospermia 4. Additionally, DNAL1 expression is reduced upon diesel exhaust particle exposure, contributing to ciliary dysfunction 5.