CCNO and Hydrocephalus: Moreover, hydrocephalus is frequently observed across murine motile-cilia gene knockouts (e.g., DNAH5, DNAAF1) but remains uncommon in human PCD except in rare ciliogenesis disorders (e.g., CCNO, FOXJ1), underscoring a rodent–human discrepancy (Sakamoto et al., 2021; Ha et al., 2016; Eisenhuth et al., 2025).