DNAAF5 (dynein axonemal assembly factor 5) is a cytoplasmic protein essential for delivering dynein motor machinery to motile cilia 1. It functions as a dynein motor assembly factor required for the assembly of axonemal dynein inner and outer arms, which are critical structures attached to peripheral microtubules that enable cilium motility 12. DNAAF5 operates as part of an early preassembly complex with other dynein-associated proteins during cytoplasmic preassembly of dynein before trafficking into cilia 3. Biallelic pathogenic variants in DNAAF5 cause primary ciliary dyskinesia (PCD), an autosomal recessive disorder characterized by impaired ciliary function 14. Disease severity exhibits allele-specific and tissue-specific variation; null mutations are embryonic lethal, while missense mutations permit partial cilia function preservation with variable severity across multiciliated tissues 12. DNAAF5 variants rank among the most prevalent causes of PCD, identified in ~14% of patients in consanguineous populations 4. Neonatal PCD diagnosis has been achieved through targeted genetic testing of DNAAF5 variants 5. Beyond ciliary disease, a genome-wide association study identified an intronic DNAAF5 variant associated with increased cerebrospinal fluid phosphorylated tau levels across neurodegenerative diseases, suggesting potential broader neurobiological relevance 6.