TTC29 (tetratricopeptide repeat domain 29) is an axonemal protein essential for flagellar structure and function in sperm. It localizes to the sperm flagellum and regulates flagellar assembly, beating, and sperm motility through organization of axonemal and peri-axonemal structures 1. TTC29 functions as a component of a multi-protein complex that includes ZMYND12 and DNAH1 (a dynein arm protein), which together regulate inner dynein arm organization critical for proper flagellar beating 2. The protein contains tetratricopeptide repeat domains and interacts with intraflagellar transport complex components, including TTC30A and IFT52, facilitating their axonemal localization 1. Biallelic mutations in TTC29 cause multiple morphological abnormalities of the flagella (MMAF), characterized by immotile sperm with absent, short, bent, or irregular flagella 13. Affected individuals present severe asthenoteratospermia with dramatic disorganization of axonemal ultrastructure and reduced sperm motility, resulting in male subfertility 1. Animal models confirm TTC29 mutations cause identical flagellar defects and male subfertility 1. Clinically, TTC29-associated male infertility can be addressed through intracytoplasmic sperm injection (ICSI), which achieves satisfactory reproductive outcomes despite the severe flagellar pathology 1.