GRAF function is affected by mutations and deletions of the gene in patients with acute myeloid leukaemia (AML) or myelodysplastic syndrome (MDS) (Borkhardt et al, 2000) and we hypothesised that GRAF function could also be affected by downregulation induced by methylation of its promoting regions as shown for established tumour suppressor genes (e.g. hMLH1, HIC1, E-cad, VHL, CDKN2, RB, BRCA1) (Herman et al, 1994, 1998; Gonzalez-Zulueta et al, 1995; Yoshiura et al, 1995; Dobrovic and Simpfendorfer, 1997; Graff et al, 1997; Jarrard et al, 1997; Ohtani-Fujita et al, 1997; Melki et al, 1999). The gene discussed is ARHGAP26; the disease is myelodysplastic syndrome.