ARMC4 is an axonemal protein that is necessary for proper targeting and anchoring of outer dynein arm complexes (ODAs). Respiratory cells from individuals with ARMC4 mutations that predict premature termination of translation show a severe ODA defect. The ciliary beat is slow, and some cilia are immotile. The p.Leu927Trp variation retains some residual function: using electron microscopy analysis, some ODA complexes are still visible. These cilia show a much milder phenotype.