L1CAM is a membrane-associated signalling molecule that is essential for proper CST development.
L1CAM appears to act as a receptor in conjunction with neuropilin-1, transducing a signal from Sema3A that drives CST fibres dorsally as they cross the ventral medullary–cervical junction.
L1cam is an enteric neural system-expressed gene.
Pathology
L1CAM mutations result in many CST fibres aborting prior to the decussation, with a few fibres projecting to ectopic spinal cord locations.
Mutations of the human L1CAM gene result in CST misdevelopment and a clinically variable phenotype that includes a spastic, uncoordinated gait.
L1CAM germline mutations in
- X-linked hydrocephalus (MIM.307000)
- MASA syndrome (MIM.303350)
- X-linked complicated spastic paraplegia type 1
- X-linked agenesis of the corpus callosum
- X-linked hydrocephalus by stenosis of the aqueduct of Sylvius (MIM.307000) and congenital idiopathic intestinal pseudoobstruction (MIM.300048)
- X-linked hydrocephalus (MIM.307000) with Hirschsprung disease (MIM.142623)
Indeed, at least five different mutations in L1CAM have been identified in patients with hydrocephalus and HSCR. The question of L1CAM being a modifier gene in HSCR has been raised with no definitive answer given thus far.
References
Kenwrick S, Watkins A, De Angelis E. Neural cell recognition molecule L1: relating biological complexity to human disease mutations. Hum Mol Genet. 2000 Apr 12;9(6):879-86. PMID: 10767310
Fransen E, Van Camp G, Vits L, Willems PJ. L1-associated diseases: clinical geneticists divide, molecular geneticists unite. Hum Mol Genet. 1997;6(10):1625-32. PMID: 9300653