DNA methylation changes in leukaemia.

Leukaemogenesis is a multi-step process whereby a clonal population arises that has undergone successive alterations to the genotype and the phenotype of the cells that make up the clone. Leukaemia has traditionally been viewed as a genetic disease, however epigenetic defects also play an important role. Expression of the DNA methyltransferase enzymes is elevated in leukaemia, and aberrant methylation is common with both a decrease in the total genomic 5-methylcytosine, and a concomitant hypermethylation of CpG island-associated tumour suppressor genes. This review will discuss the multitude of DNA methylation changes in haematopoietic malignancies and the implications they have for diagnosis and treatment.