DNAH3 (dynein axonemal heavy chain 3) is a force-generating motor protein of respiratory cilia and sperm flagella that produces force toward microtubule minus ends 1. The protein exhibits ATPase activity and is essential for assembling and organizing the sperm flagellum's axoneme, particularly the inner dynein arms 12. DNAH3 deficiency causes male infertility through multiple mechanisms. Biallelic DNAH3 variants have been identified in infertile men presenting with asthenozoospermia or oligoasthenoteratozoospermia (OAT), characterized by reduced sperm motility and flagellar morphological abnormalities 132. In affected patients, DNAH3 loss leads to decreased expression of IDA-associated proteins including DNAH1, DNAH6, and DNALI1, coupled with ultrastructural defects such as inner dynein arm loss, dislocated mitochondrial sheaths, and fibrous sheath abnormalities 12. Notably, DNAH3 deficiency can also impair sperm energy metabolism without flagellar morphological changes, reducing metabolites like L-palmitoylcarnitine and glycocholic acid 4. Clinically, DNAH3-associated male infertility can be effectively managed through intracytoplasmic sperm injection (ICSI), indicating the defect is exclusively in sperm motility function rather than fundamental genetic abnormality 124. These findings establish DNAH3 as a novel pathogenic gene for male infertility with diagnostic and prognostic implications.