The diagnostic criteria for familial CJD (fCJD or gCJD) include definite or probable CJD plus definite or probable CJD in a first-degree relative and/or a neuropsychiatric disorder plus disease-specific PRNP gene mutation (http://www.cdc.gov/prions/cjd/diagnostic-criteria.html). The gene discussed is PRNP; the disease is Creutzfeldt Jacob disease.