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]. This evidence concerns the gene L1CAM and adducted thumbs-arthrogryposis syndrome, Christian type.