APOE and Hydrocephalus: In addition, although ependymal maturation is mainly a gene-controlled process, late findings have shown EC ciliogenesis is metabolically regulated, which comes in accordance with studies suggesting that metabolic dysregulation is involved in hydrocephalus pathophysiology (Caner et al., 1993; Kondziella et al., 2008; Lummis et al., 2019) and that ECs secrete a variety of metabolic products, such as apolipoprotein E (APOE) (Lee et al., 2012).