A comparable phenomenon was observed in 58 Tunisian patients with PCD in whom CCDC39 and c.2190del in CCDC39 was a mutation hotspot, whereas deleterious mutations in CCDC39 or CCDC40 were rarely observed in Chinese patients with PCD and only one case involved CCDC40 dysfunction [30]. This evidence concerns the gene CCDC39 and primary ciliary dyskinesia.