Congenital hydrocephalus-4 (HYC4) is characterized by inadequate passage of cerebrospinal fluid (CSF) from its point of production to its point of absorption, in the absence of obstruction (communicating hydrocephalus). Patients undergo surgical shunting at birth because of extreme ventriculomegaly. Patients have neurodevelopmental delay and epilepsy (Furey et al., 2018). [from OMIM]