DNAAF4 and primary ciliary dyskinesia: In addition, loss-of-function mutations in DYX1C1 and DCDC2 have been found in patients showing typical ciliary deficits: DYX1C1 in patients with PCD [15] and DCDC2 in patients with nephronophthisis-related ciliopathy, inherited deafness and neonatal sclerosing cholangitis [16–19].