DNA micro-array analysis of myelodysplastic syndrome

Myelodysplastic syndrome (MDS) is an enigmatic disorder characterized by ineffective hematopoiesis and dysplastic morphology of blood cells. The clinical course of MDS consists of distinct stages, with early stages often progressing to advanced ones or to acute myeloid leukemia (AML). Little is known of the molecular pathogenesis of MDS or of the mechanism of its stage progression. DNA micro-array analysis, which allows simultaneous monitoring of the expression levels of tens of thousands of genes, has the potential to provide insight into the pathophysiology of MDS. Several studies have applied this new technology to compare gene expression profiles either between MDS and the healthy condition, among the different stages of MDS or between MDS-derived AML and de novo AML. Selection of an appropriate hematopoietic fraction is important for such studies, which to date have been performed with differentiated granulocytes, CD34 + progenitors and CD133 + immature cells. These studies have revealed that each stage of MDS has its own 'molecular signature, indicating the feasibility of differential diagnosis of MDS based on gene expression profile. They have also demonstrated that the current clinical diagnosis of MDS results in the misclassification of patients with regard to these molecular signatures.