CCDC40 and primary ciliary dyskinesia: Among 32 genes in which defects lead to primary ciliary dyskinesia, six (Dnaic2, Ccdc40, Armc4, Ccdc164/DRC1, Rsph9, Ccdc11) are strongly downregulated in Rfx2-/- testes at both time points, and three others only at P30 (Ccdc65, Zmynd10, Ccno) (for review see [72]).