FOXJ1 and Hydrocephalus: Defects in motile cilia structure and function disrupt the near-wall directional movement of CSF and lead to hydrocephalus, albeit via unclear mechanisms (Kumar et al. 2021). We found that mice with heterozygous Foxj1 mutations display aberrant rotational and planar cell polarity as well as turbulent, disorganized flow in the lateral ventricles.