Fatal familial insomnia (FFI) and a subtype of familial Creutzfeldt-Jakob disease (CJD), two clinically and pathologically distinct diseases, are linked to the same mutation at codon 178 (Asn178) of the prion protein gene.
(1991) reported an association between homozygosity in a polymorphic site at codon 129 of the PrP gene, coding for either valine or methionine, with a tendency to acquire the sporadic or iatrogenic forms of CJD, as well as with disease age of appearance in the genetic type.
Using this system, we found a new mutation of the PrP gene in a patient with pathologically confirmed Creutzfeldt-Jakob disease and a negative family history for dementia.