A DUPLICATION IN THE L1CAM GENE ASSOCIATED WITH X-LINKED HYDROCEPHALUS

Recently, a mutation in the gene for the neural cell adhesion molecule L1CAM, located at chromosome Xq28, was found in a family with X-linke d hydrocephalus (HSAS). However, as the L1CAM mutation could only be i dentified in one HSAS family, it remained unclear whether or not L1CAM was the gene responsible for HSAS. We have conducted a mutation analy sis of L1CAM in 25 HSAS families. The mutation reported previously was not found in any of these families. In one family, however, a 1.3 kil obases (kb) genomic duplication was identified, cosegregating with HSA S and significantly changing the intracellular domain of the L1CAM pro tein. These results confirm that L1CAM is the HSAS gene.