DNAH1 (dynein axonemal heavy chain 1) is a critical motor protein component of sperm flagella required for male fertility. DNAH1 functions as part of the inner dynein arms (IDAs) within the axoneme, generating force toward the minus ends of microtubules through ATP hydrolysis to drive flagellar motility 1. The protein is essential for proper sperm flagellum assembly and biogenesis, with deficiency leading to multiple morphological abnormalities of sperm flagella (MMAF) and dysplasia of the fibrous sheath 2. DNAH1 forms functional complexes with other axonemal proteins including DNALI1, TTC29, and ZMYND12, which are crucial for flagellum structure and motility 13. Mutations in DNAH1 are associated with asthenoteratozoospermia and male infertility, with studies identifying multiple pathogenic variants in infertile Chinese men 42. Interestingly, DNAH1 mutations are also linked to primary ciliary dyskinesia (PCD), particularly in pediatric cases presenting with postinfectious bronchiolitis obliterans 5. The protein's dysfunction results in absent or severely reduced DNAH1 expression in sperm, leading to shortened or coiled sperm tails and compromised fertility 2. These findings establish DNAH1 as a key diagnostic marker for genetic male infertility and highlight the importance of assisted reproductive technologies for affected individuals.