5q- syndrome is a subtype of myelodysplastic syndrome (MDS) characterized by bone marrow erythroid hyperplasia, atypical megakaryocytes, thrombocythemia, refractory anemia, and low risk of progression to acute myeloid leukemia (AML) compared with other types of MDS. The WHO has proposed diagnostic criteria for the 5q- syndrome, defining the syndrome as representing de novo MDS, with a 5q interstitial deletion between bands 31 and 33 as the sole cytogenetic abnormality, macrocytic anemia, less than 5% blasts in the peripheral blood, and a normal or increased platelet count. The 5q- syndrome is also unique because it shows a remarkable response to treatment with the lenalidomide. It has been suggested that the 5q- syndrome is caused by haploinsufficiency of the ribosomal protein S14 (RPS14) gene which maps to the commonly deleted region.
