The neural cell adhesion molecule L1CAM has been reported to have functional roles in the developing and adult nervous system, and a knock-out mouse mutation of L1 has been associated with the L1 syndrome (Kamiguchi et al., 1998; Hortsch, 2000; Loers and Schachner, 2007; Maness and Schachner, 2007; Schmid and Maness, 2008; Schafer and Altevogt, 2010; Hortsch et al., 2014; Sytnyk et al., 2017). This evidence concerns the gene CHL1 and L1 syndrome.