تخلف عقلي
Intellectual disability in LFS usually ranges from mild to moderate, but severe cases have also been reported. A relatively common brain anomaly seen with LFS is agenesis of the corpus callosum, an error of embryonic development in which the corpus callosum (a structure of the mammalian brain composed of nerves that allows communication between the left and right cerebral hemispheres) is not present. Among a number of adverse neurological effects sometimes found with an absence of the corpus callosum, intellectual disability has been shown to occur at a rate of approximately 73 percent. A correlation between agenesis of the corpus callosum and intellectual disability in LFS, however, has not been suggested.