CFAP47 is an X-linked cilia and flagella-associated protein essential for sperm motility and axoneme structure. Primary function: CFAP47 serves as a core structural component of the central apparatus within the sperm axoneme, where it tethers C1 and C2 microtubules through N-terminal domains that bind C1, a central CFAP47-ring that interacts with HYDIN, and C-terminal regions anchoring to C2 1. Mechanism: The protein is highly expressed in testis and localizes to the sperm flagellar midpiece, where it interacts with WDR87 to facilitate proper flagellar assembly and spermatozoa tail development 2. Disease relevance: Hemizygous mutations in CFAP47 cause X-linked asthenoteratozoospermia with multiple morphological abnormalities of the flagella (MMAF), characterized by reduced sperm motility, abnormal flagellar morphology, and defective sperm head/mitochondrial organization 34. Additionally, CFAP47 variants are implicated in primary ciliary dyskinesia (PCD) affecting respiratory epithelial cells 5 and X-linked polycystic kidney disease through disrupted primary cilia function 6. Clinical significance: Male infertility due to CFAP47 mutations shows good prognosis with intracytoplasmic sperm injection (ICSI), while identification of CFAP47 variants enables precise genetic counseling and targeted reproductive interventions 37.