Familial transmissible spongiform encephalopathies comprise about 14% of all cases of transmissible spongiform encephalopathy in humans. We report on a patient with a definite diagnosis of familial Creutzfeldt-Jakob disease with an insertional mutation consisting of seven extra octapeptide repeats between codons 51 and 91 in the PRNP gene, associated with a genotype homozygotic for methionine at codon 129 and a novel coding change of the inserted octapeptide region.