CJD was suspected and PRNP analysis confirmed a heterozygous c.598G>A (p.(Glu200Lys) or E200K) mutation with a heterozygous Valine (V) / Methionine (M) codon 129 polymorphism, with a Methionine (M) on the mutated allele. The gene discussed is PRNP; the disease is Creutzfeldt Jacob disease.