A myelodysplastic syndrome characterized by a deletion between bands q31 and 33 on chromosome 5. the number of blasts in the bone marrow and blood is <5%. the bone marrow is usually hypercellular or normocellular with increased number of often hypolobated megakaryocytes. the peripheral blood shows macrocytic anemia. this syndrome occurs predominantly but not exclusively in middle age to older women. the prognosis is good and transformation to acute leukemia is rare. (who, 2001)