DNALI1 (dynein axonemal light intermediate chain 1) is essential for sperm flagellum assembly and male fertility. The protein functions as a light intermediate chain component of inner dynein arms (IDAs) in the axoneme structure of sperm flagella 1. DNALI1 specifically associates with DNAH1 and DNAH7 dynein heavy chains rather than DNAH10, defining it as a component of a partial IDA subspecies 1. Beyond its classical dynein role, DNALI1 regulates cytoplasmic dynein complexes that transport and assemble fibrous sheath proteins, particularly AKAP3 and AKAP4, during flagellogenesis 1. DNALI1 also interacts with DNAH12 for proper IDA recruitment and axoneme organization 2. Loss-of-function mutations in DNALI1 cause severe asthenozoospermia and male infertility in both humans and mice, characterized by disrupted flagellar ultrastructure, asymmetric fibrous sheath distribution, and impaired sperm motility 134. The protein is specifically required for sperm function rather than ciliary motility 2. Clinically, DNALI1 deficiency represents a causative factor for spermatogenic failure, but affected individuals can achieve fertility through intracytoplasmic sperm injection (ICSI) 134.