L1CAM and Hydrocephalus: Interestingly, through investigation of the literatures, we found that 2 mutations (S1226L and Y1231H conversions) in the L1CAM ABD (illustrated in Fig. 6E) have been linked to L1 syndrome, an inherited mild to severe congenital disorder characterized by corpus callosum hypoplasia, retardation, adducted thumbs, spastic paraplegia, and hydrocephalus (36, 37, 38).