CRASH syndrome: clinical spectrum of corpus callosum hypoplasia, retardation, adducted thumbs, spastic paraparesis and hydrocephalus due to mutations in one single gene, L1

Eur J Hum Genet. 1995;3(5):273-84. doi: 10.1159/000472311.


L1 is a neuronal cell adhesion molecule with important functions in the development of the nervous system. The gene encoding L1 is located near the telomere of the long arm of the X chromosome in Xq28. We review here the evidence that several X-linked mental retardation syndromes including X-linked hydrocephalus (HSAS), MASA syndrome, X-linked complicated spastic paraparesis (SP1) and X-linked corpus callosum agenesis (ACC) are all due to mutations in the L1 gene. The inter- and intrafamilial variability in families with an L1 mutation is very wide, and patients with HSAS, MASA, SP1 and ACC can be present within the same family. Therefore, we propose here to refer to this clinical syndrome with the acronym CRASH, for Corpus callosum hypoplasia, Retardation, Adducted thumbs, Spastic paraplegia and Hydrocephalus.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.
  • Review

MeSH terms

  • Abnormalities, Multiple / genetics*
  • Agenesis of Corpus Callosum
  • Diagnosis, Differential
  • Genetic Linkage
  • Genotype
  • Humans
  • Hydrocephalus / genetics
  • Intellectual Disability / genetics
  • Leukocyte L1 Antigen Complex
  • Movement Disorders / genetics
  • Mutation*
  • Neural Cell Adhesion Molecules / genetics*
  • Paraplegia / genetics
  • Phenotype
  • Prenatal Diagnosis
  • Sex Chromosome Aberrations / diagnosis
  • Sex Chromosome Aberrations / genetics*
  • Syndrome
  • Thumb / abnormalities
  • X Chromosome*


  • Leukocyte L1 Antigen Complex
  • Neural Cell Adhesion Molecules