Creutzfeldt-Jakob disease (CJD) is an uncommon neurodegenerative disorder with an incidence of 1 per 1,000,000 in humans per year, typically characterized by rapidly progressive dementia, ataxia, myoclonus and behavioral changes. Genetic prion diseases, which develop due to a mutation in the prion protein gene (PRNP), account for an estimated 10 to 15% of all CJD cases. Familial CJD is transmitted with an autosomal dominant inheritance pattern with high penetrance. Worldwide, the most common mutation is E200K (glutamate to lysine). We report four families with CJD assisted in Neuquén Hospital in 2018. Three of the four index cases had family history of neurological and psychiatric illness, though data was not taken into consideration at the moment of evaluation of the new cases. The most significant data recorded for a genetic consultation was when the problem had started, and it was required by a neurologist. The initial symptoms were persistent insomnia and depression with poor response to habitual psychiatric medication. Impoverishment is fast with visual disorder, myoclonias, ataxia, dementia and loss of language. Pedigree analysis allowed the identification of 144persons with the gene potential, who can develop the disease at any time in their adulthood. In all cases, mutation E200K was identified. There is a region of increased frequency of CJD. There must be suspicion on patients with neuropsychiatric symptoms and suspected family history(familiar background). Finding of the mutation confirms the diagnosis in patients and allows the identification on pre-symptomatic individuals. Challenge is posed on gene advice and to avoid iatrogenic disorder transmission. Key words: Familial Creutzfeldt-Jakob Syndrome, PRNP gene, E200K, CJD in Patagonia