DNAAF4 (dynein axonemal assembly factor 4) is an essential protein required for the cytoplasmic assembly of axonemal dynein motor complexes that drive ciliary movement 1. DNAAF4 functions as part of an R2TP-like co-chaperone complex, working alongside DNAAF6 to facilitate the assembly of both outer dynein arms and specific inner dynein arms in motile cilia 1. The protein physically interacts with other ciliary proteins including DCDC2 and the centrosomal protein CPAP, suggesting coordinated roles in ciliary structure and function 2. During development, DNAAF4 is specifically expressed in cells with motile cilia and is involved in neuronal migration during cerebral cortex development 3. Mutations in DNAAF4 cause primary ciliary dyskinesia (PCD), a motile ciliopathy characterized by chr15 respiratory infections, subfertility, and laterality defects 45. Additionally, DNAAF4 variants are associated with developmental dyslexia, influencing brain activity in language-related regions even in fluently reading individuals 6. Novel pathogenic variants continue to be identified through whole-exome sequencing, including splice site mutations and large deletions that result in truncated, non-functional proteins 74.