Mutations in L1CAM are causative for a wide range of neurological defects referred to as L1 or CRASH syndrome [206,207,208] and it is noteworthy here that proteolytic cleavage of L1CAM by myelin basic protein leads to the generation of a 70 kDa transmembrane L1 fragment that is imported from the cytoplasm into mitochondria and promotes neuronal migration and neuritogenesis [209]. Here, L1CAM is linked to L1 syndrome.