Trp73−/− mice show congenital hydrocephalus, hippocampal dysgenesis, absence of the hippocampal sulcus (a folding defect), decreased expression of reelin and calretinin (markers of Cajal-Retzius neurons) in the cortical marginal zone and hippocampal molecular layer, frontal cortex hypoplasia, occipital cortex dyslamination, ventralized cortical patterning with expanded entorhinal-like cortex, increased cortical apoptosis, and probably aberrant connections [44,45]. This evidence concerns the gene RELN and Hydrocephalus.