All other neuroblastoma tumours (64 of 68; 94%) showed methylated RASSF1A. Hypermethylation in tumours was observed very frequently in all of the stages of neuroblastoma examined, including stage 1, 2 and 4S tumours (Supplementary Table) and no correlation between RASSF1A methylation and known prognostic factors including stage, age and MYCN amplification was detected. This evidence concerns the gene RASSF1 and neuroblastoma.