Clinical significance of cytogenetic manifestations in myelodysplastic syndromes

Myelodysplastic syndrome (MDS) represents a heterogeneous hematopoietic stem-cell disorder that results in abnormal cellular maturation and peripheral blood cytopenias. MDS is characterized by progressive bone marrow failure, which can lead to bleeding, infections, and complications secondary to anemia. Approximately 35% to 40% of patients diagnosed with MDS progress to acute myeloid leukemia (AML), which confers a poorer prognosis. MDS may develop de novo without underlying risk factors or may be secondary, occurring after exposure to chemotherapeutic agents or ionizing radiation. The earliest attempt to classify MDS into various subgroups was by the French-American-British (FAB) group, which separated MDS by its morphologic and clinical characteristics, such as the percentage of blasts in bone marrow. The progression of disease in patients with MDS is extremely variable, however, reflecting the heterogeneity of this syndrome. Although the FAB classification system has been useful, it has proven to be inaccurate when determining a patient's prognosis. As studies have evolved, the genetic heterogeneity of MDS has proven to be a clear reason that the FAB classification system is prognostically insufficient. More than 50% of patients with MDS have clonal cytogenetic abnormalities, and the molecular consequences of these abnormalities continue to be elucidated. The chromosomal abnormalities in MDS have helped to stratify the myelodysplastic syndromes into poor-, intermediate-, and good-prognosis groups.