- Polymorphisms in the prion protein gene and in the doppel gene increase susceptibility for Creutzfeldt-Jakob disease. Croes, E.A., Alizadeh, B.Z., Bertoli-Avella, A.M., Rademaker, T., Vergeer-Drop, J., Dermaut, B., Houwing-Duistermaat, J.J., Wientjens, D.P., Hofman, A., Van Broeckhoven, C., van Duijn, C.M. Eur. J. Hum. Genet. (2004)