DNAH2 encodes a dynein axonemal heavy chain protein that functions as part of the inner dynein arm complex in cilia and flagella. As a microtubule-based molecular motor with ATPase activity, DNAH2 converts ATP chemical energy into mechanical force to generate ciliary and flagellar bending through sliding between adjacent microtubule doublets 1. The protein is specifically expressed in sperm flagella where it is essential for sperm motility 1. DNAH2 mutations cause multiple morphological abnormalities of sperm flagella (MMAF), a severe form of teratozoospermia characterized by absent or shortened flagella, disarranged axonemal structures, mitochondrial defects, and loss of inner dynein arms 123. Patients with DNAH2 mutations present with asthenoteratozoospermia and male infertility, classified as spermatogenic failure 45 4. Despite severe sperm structural defects, the nuclear quality remains intact, allowing successful reproduction through intracytoplasmic sperm injection (ICSI) with favorable clinical outcomes including live births 123. DNAH2 has also been identified as a candidate gene in chr17 myelomonocytic leukemia through whole-exome sequencing studies 5.