Codon 200 mutation in a new family of Chilean origin with Creutzfeldt-Jakob disease.

Codon 200 mutation in a new family of Chilean origin with Creutzfeldt-Jakob disease Creutzfeldt-Jakob disease is a fatal progres- sive transmissible dementia, with a worldwide incidence of 0-5-1-0 cases per million.In some populations, such as Libyan Jews and Slovaks from the Orava region, there is a high incidence of Creutzfeldt-Jakob disease which is associated with a mutation at codon 200 of the prion protein gene (PRNP).'The same mutation was identified in six families with Creutzfeldt-Jakob disease from Chile, where the disease has a high fre- quency and is familial in about half of the cases.2 We describe an additional Chilean family carrying this mutation.The figure shows the pedigree of the fam- ily.The proband (V-1) was a 56 year old Chilean woman who, in the early 1990s, became seriously depressed.Five months later, she showed progressive mental deteri- oration, cortical blindness, ataxia, tremor, dymetria, hypotonia, and sporadic bursts of myoclonic jerks.She had repeated gener- alised tonic-clonic seizures and the EEG recorded slow background activity with peri- odic discharges.The patient died nine months after the onset of symptoms.At neu-III on