OBJECTIVETo analyze the clinical and cytogenetic features of myelodysplastic syndrome(MDS) associated with del(20q).

METHODSThe cytogenetic profiles, clinical manifestations, laboratory data, and transformation in course of disease were analyzed.

RESULTS(1) Of 29 MDS patients with del(20q), eleven (37.9%) had normal karyotype in addition to del(20q) aberration. Among them, nine patients were categorized into refractory anemia(RA)/RA with ringed sideroblasts(RAS) group and two into RA with excess Hasts(RAEB)/RAEB in transformation(RAEB-T) group. The breakpoint in 20q11 was commonly seen in patients with RA/RAS(63.2%), while del(20q12) was predominant in patients with RAEB/RAEB-T(accounting for 70% in all RAEB/RAEB-T patients). It was observed that RAEB/RAEB-T patients had higher frequencies of extra chromosomal aberrations(50%) and complex karyotype(30%) than did the RA/RAS patients (26.3%, 5.3% respectively); (2) Almost all patients revealed prominent pancytopenia, dyserythropoiesis and dysgranulopoiesis and 58.6% patients showed dysmegakaryopoiesis; positive periodic acid schiff staining of nucleated erythrocytes or reduction of neutrophils were found in 62.5% of patients; 81.8% of patients expressed lymphoid antigens; (3) Two cases transformed to acute myeloid leukemia.

CONCLUSIONDel(20q) may be an early and primary cytogenetic event in the development of hematologic malignancies. Pancytopenia and dysplasia of bone marrow cells are prominent in patients with MDS associated with del(20q); lymphoid antigen expression is a common occurrence; more additional chromosomal abnormalities and complex karyotypes appear when the disease becomes worse.