CCDC40 and primary ciliary dyskinesia: Given the fact that none of the cases included in this study had a formal diagnosis of PCD nor was suspected with PCD clinically, we identified pathogenic or likely pathogenic variants in a rather large number of genes known to cause PCD when dysfunctional, including DNAH5, DNAH9, CCDC114, DNAI1, DNAI2, CCDC39, and CCDC40. DNAH5 encodes an outer dynein arm γ—heavy chain distributed panaxonemally in respiratory cilia, and biallelic loss of function mutations are a frequent cause of PCD (Hornef et al., 2006).