This study will explore how processes that regulate gene expression can be dramatically deregulated in human diseases. Understanding how, when, and where can tremendously impact on disease management, prevention and treatment. This project will look at one of these processes: DNA methylation (the addition of methyl marks to the DNA molecules) in patients with genetic prion diseases. The aim is to correlate these marks with disease onset and to develop markers to track the disease in patients, with the purpose of making clinical trials more feasible.