DNAAF5 and primary ciliary dyskinesia: Since it has been difficult to recapitulate unidirectional mucociliary flow using hiPSC-derived airway epithelium in vitro, Sone et al. utilized a complex airway on a chip technology to demonstrate that abnormal mucociliary transport and altered ciliary ultrastructure, both hallmarks of PCD that are detectable in primary material, are also detectable in PCD patient-derived hiPSC with different underlying mutations (HEATR2, DNAH11, and PIH1D3) [24].