Identification of novel mutations in L1CAM gene by a DHPLC-based assay

X-linked hydrocephalus, MASA syndrome, X-linked complicated Spastic Paraplegia Type I, and X-linked partial agenesis of the corpus callosum are rare diseases mainly affecting male population and broadly referred as L1 syndrome, caused by mutations in the L1CAM gene. In the present study 36 boys and a male fetus whose clinical features were consistent with L1 syndrome were analyzed by dHPLC assay and direct sequencing of L1CAM gene. Sequence analysis of the 14 different aberrant dHPLC elution profiles demonstrated that six of them were associated with already reported polymorphisms, four with previously described causative variants while the remaining four represented novel L1CAM mutations. The dHPLC method proposed identified eight (21 %) causative L1CAM mutations in our patients while direct sequencing failed to detect any variation in patients negative to dHPLC analysis. We conclude that the dHPLC assay represents a fast and efficient method for the screening of L1CAM mutations and that L1 syndrome should be considered in the differential diagnosis of intellectual disability in children, especially when other signs such as hydrocephalus or adducted thumbs are present.