Mice carrying loss‐of‐function mutations (LOF) in either L1CAM (Dahme et al, 1997; Rolf et al, 2001) or MPDZ (Feldner et al, 2017) developed severe hydrocephalus similar to human carriers of biallelic L1CAM (Kanemura et al, 2006) and MPDZ mutants (Al‐Dosari et al, 2013; Saugier‐Veber et al, 2017). Here, L1CAM is linked to Hydrocephalus.