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. Here, CTSF is linked to neuronal ceroid lipofuscinosis.