CFAP74 (cilia and flagella associated protein 74) is a component of the ciliary central apparatus that plays critical roles in both ciliary function and sperm architecture. As part of the central apparatus of the cilium axoneme, CFAP74 contributes to cilium movement and is essential for proper axoneme assembly 1. During spermiogenesis, CFAP74 mRNA is translationally regulated by CEP112 through phase separation-mediated RNA granule formation, indicating its importance in sperm development 2. Pathogenic biallelic mutations in CFAP74 cause primary ciliary dyskinesia (PCD), particularly the C1d-defective subtype, characterized by defective central apparatus projections 3. This PCD variant presents atypically with normal nasal nitric oxide levels, normal ciliary ultrastructure by electron microscopy, and normal ciliary beating patterns, yet exhibits impaired mucociliary clearance in vitro 3. CFAP74 variants also cause severe male infertility through multiple morphological abnormalities of the flagella (MMAF) and asthenoteratozoospermia, resulting in characteristic flagellar defects including disorganized mitochondrial sheath and axonemal structural abnormalities 1, 4. CFAP74 localizes along the entire sperm flagella and interacts with other flagellar development proteins like CFAP221 5. Despite severe fertility impairment from CFAP74 mutations, intracytoplasmic sperm injection (ICSI) can enable successful pregnancy 1, 4, providing important clinical guidance for affected patients.