The small sample size was likely a factor for the lack of variation in the phenotype between the two groups. Also of note, of the five patients homozygous for the c.598G>A (p.E200K) variant, all but one had detectable levels of PrP. Additional analyses of genetic CJD cases with homozygous PRNP variants would be necessary to fully characterize the difference between heterozygous and homozygous PRNP variants. Here, PRNP is linked to Creutzfeldt Jacob disease.