Gene-specific hypermethylation was first described for the RB gene in retinoblastoma (Greger et al., 1989) and many other tumour suppressor genes have been reported as methylated in tumours, for example p16, VHL, MLH1, APC and E-cadherin (reviewed in (Jones and Baylin, 2002)). This evidence concerns the gene CDKN2A and neoplasm.