CTSF mutations have recently been identified as causing type B Kufs disease, an adult-onset neuronal ceroid lipofuscinosis, associated with a severe, early-onset neuropsychiatric phenotype with early epileptic seizures,21, 37 and more recently one family with early-onset AD phenotype has been reported.38 We now show that an adult-onset FTD phenotype, without seizures, can also be caused by CTSF mutations, thus extending the genetic and molecular basis of clinical FTD. This evidence concerns the gene CTSF and ceroid lipofuscinosis, neuronal, 4 (Kufs type).