DNAH12 (dynein axonemal heavy chain 12) is a specialized dynein component essential for proper sperm flagella organization and male fertility. Unlike other dyneins, DNAH12 lacks a microtubule-binding domain but functions as a crucial assembly factor for inner dynein arms (IDAs) in sperm flagella 1. The protein specifically recruits DNAH1 and DNALI1 to the IDAs and interacts with radial spoke head proteins (RSPH1, RSPH9, DNAJB13) to regulate central pair stability 1. DNAH12 shows tissue-specific expression, being primarily found in spermatocytes and early spermatids during spermatogenesis 2. Importantly, DNAH12 deficiency affects sperm flagella organization but not cilia function 1. Biallelic mutations in DNAH12 cause male infertility characterized by severe asthenoteratozoospermia, with transmission electron microscopy revealing pronounced axonemal abnormalities including IDA impairment and central pair loss 13. Mouse models confirm the reproductive phenotype, demonstrating spermatogenesis failure 3. Clinically, DNAH12 variants are associated with spermatogenic failure, and intracytoplasmic sperm injection (ICSI) has proven effective for achieving fertility in affected patients and mouse models 13. These findings establish DNAH12 as an important diagnostic marker for male infertility genetic counseling.