L1CAM and Hydrocephalus: Autosomal recessive mutations in NT5C2 are the cause of spastic paraplegia type 45 and are associated with ID.29 Finally, a novel X-linked likely pathogenic variant was identified in L1CAM (NM_001143963.2: c.2137C>T: p.P713S), mutations in which cause CRASH syndrome (corpus callosum hypoplasia, retardation, aphasia, spastic paraplegia and hydrocephalus).