The risk of developing Creutzfeldt-Jakob disease in subjects with the PRNP gene codon 200 point mutation.

We determined the penetrance of the PRNP 200Lys mutation in the large cluster of Creutzfeldt-Jakob disease (CJD) cases among Jews of Libyan-Tunisian origin living in Israel, utilizing data from 52 carriers with definite or probable CJD and 34 unaffected mutation carriers. A life table analysis was carried out with development of CJD as the end point. The probability of developing CJD rose with age, fitting a second-order regression curve (R = 0.97, p < 0.001). The cumulative penetrance reached 50% at the age of 60 and 80% at 80 years. Including seven elderly possible CJD patients in the analysis made the penetrance approach 100% by age eighty. The penetrance of the mutation is high, and although age is a predominant influencing factor, other factors, such as gender, may also play a role.