The MRI findings of L1CAM-associated hydrocephalus is characterized by severe dilatation of the third and lateral ventricles, aqueduct stenosis, enlarged quadrigeminal plates, interthalamic adhesion hypertrophy, thinning of the corpus callosum, hypoplasia of the cerebellar vermis, and adducted thumbs (Fig. 4). Here, L1CAM is linked to Hydrocephalus.