An assay for assessing the risk of disease in an individual, wherein said assay comprises the steps of isolating a population of cells from normal tissue of said individual, and quantitatively determining the frequency of epimutation of a particular gene in said population of cells, wherein the epimutation of said gene is associated with said disease and said gene is other than one that is subject to normal parent of origin-specific expression. Preferably, the epimutation is DNA methylation of a tumour suppressor gene such as hMLH1, hMSH2, APC 1A, APC 1B and p16.