CFAP43 is a ciliary and flagellar protein essential for axoneme organization and motile cilia function. The protein localizes to the ciliary axoneme, specifically positioned between doublet microtubules 5 and 6 and the paraflagellar rod 1. CFAP43 regulates the beating frequency of motile cilia in respiratory tract epithelial cells and is crucial for sperm flagellum assembly and function 2. The protein mediates intra-manchette transport during spermatogenesis, which is required for proper sperm head shaping and flagella formation 3. CFAP43 acts as a target gene of the transcription factor FOXJ1, which induces motile ciliogenesis 2. Biallelic mutations in CFAP43 cause multiple morphological abnormalities of sperm flagella (MMAF), leading to male infertility with severe disorganization of sperm axonemes 14. Additionally, CFAP43 mutations are associated with idiopathic normal pressure hydrocephalus, indicating its role in cerebrospinal fluid homeostasis through cilia dysfunction 5. Mouse models confirm that CFAP43 deficiency results in male infertility, early onset hydrocephalus, and severe mucus accumulation in nasal cavities due to impaired mucociliary clearance 2. Despite the severity of flagellar defects, patients with CFAP43 mutations can achieve successful pregnancies through intracytoplasmic sperm injection 6.