Mutations in CCDC39 (e.g. c.1072del) (Aprea et al., 2023) and CCDC40 (e.g. c.901C>T) (Liu et al., 2021) destabilize the radial spoke structure, leading to axonemal disorganization and loss of motility, as observed in primary ciliary dyskinesia (PCD). This evidence concerns the gene CCDC39 and primary ciliary dyskinesia.