DNAH9 and primary ciliary dyskinesia: Furthermore, severe asthenospermia is also revealed as one of the representative features of primary ciliary dyskinesia (PCD, OMIM: 244400), which includes a wide motile dysfunction of cilia in respiratory tract and sperm, etc. Most of the PCD cases are associated with genetic mutations, and some genes have been identified, such as DNAH5 (OMIM: 603335), DNAH9 (OMIM: 603330) and DNAH11 (OMIM: 603339), etc. [16–18].