Some neurological disorders are caused by problems in brain development. These include Fragile-X syndrome (the most common cause of inherited mental impairment) and acallosal syndrome (lack of the corpus callosum, which normally links the two cerebral hemispheres). DNF researchers are launching a new collaboration with the Departments of Medical Genetics and Pathology to identify the changes in human embryonic development that cause such neurological disorders. Developmental processes to be studied include neuronal migration, survival and differentiation, and also the pathfinding of axons and their formation of synaptic connections. See Hornung.