CCDC146 is a coiled-coil domain-containing protein essential for sperm flagellum biogenesis and male fertility 1. The protein functions as a microtubule-associated protein (MAP) located at centrosomes and multiple microtubule-related organelles during mitotic division in somatic cells 1. In spermatozoa, CCDC146 localizes to the axoneme at microtubule doublets rather than centrioles, potentially acting as a microtubule inner protein (MIP) 1. The protein is crucial for proper formation of microtubule-based organelles including the manchette, head-tail coupling apparatus, and axoneme 1. CCDC146 interacts with intraflagellar transport protein 20 (IFT20), facilitating axonemal protein transportation 2. Loss-of-function mutations in CCDC146 cause non-syndromic male infertility characterized by multiple morphological abnormalities of the flagellum (MMAF), reduced sperm motility, and oligoasthenoteratozoospermia 12. Knockout studies demonstrate that CCDC146 deficiency leads to reduced levels of axonemal proteins and severe sperm nuclear defects that impair embryonic development potential 3. Interestingly, CCDC146 has also been implicated in other contexts, including interactions with bacterial pathogens and potential roles in amyotrophic lateral sclerosis pathogenesis 45.