Mutations in the L1 cell adhesion molecule (L1CAM/SPG1), an axonal glycoprotein involved in neuronal migration and differentiation, have been identified in the following various X‐linked neurological disorders: congenital hydrocephalus; mental retardation, aphasia, shuffling gait, adducted thumbs syndrome, and agenesis of the corpus callosum [35, 36]. The gene discussed is L1CAM; the disease is congenital hydrocephalus.