CFAP45 is a microtubule inner protein (MIP) component of dynein-decorated doublet microtubules in the ciliary axoneme, essential for motile cilia and flagellar beating 1. As an AMP-binding protein, CFAP45 facilitates dynein ATPase-dependent ciliary beating by maintaining adenine nucleotide homeostasis, functioning as an AMP donor to adenylate kinase 8 (AK8) to promote ADP production 2. CFAP45 localizes in a punctate static position within the axoneme and is required for cilia stability; depletion leads to cilia bulging, loss of stability, and eventual detachment from the apical surface 3. Functionally, CFAP45 interacts with CFAP52 in sperm flagella to support microtubule sliding and motility 4. Clinically, CFAP45 mutations cause heterotaxy with congenital heart disease and asthenospermia (reduced sperm motility) 23. During embryonic development, CFAP45 is critical for left-right patterning through proper monociliary function at the Left-Right Organizer 3. Beyond ciliary function, CFAP45 methylation patterns have been identified as biomarkers in endometrial stromal tumors and showed altered methylation in PTSD patients undergoing successful treatment, suggesting broader epigenetic roles 56.