HYDIN and Hydrocephalus: The mutant genes related to motile cilium dysfunction on ependymal cells, and consequent hydrocephalus development may include Ccdc39, Celsr2, Celsr3, Cetn2, Dvl, Foxj1, Hydin, Mdnah5, Pkd1, Tg737, Daple, Dnah14, Cfap43, Cwh43, Eml1, Fmn2, Tmem67, and Zcchc8 (Law et al., 2014; Shaheen et al., 2017; Kundishora et al., 2021; McKnight et al., 2021; Yamada et al., 2021).