Objective: To analyze the clinical and molecular cytogenetic features of hematologic malignancies with idic(20q-).
Methods: The clinical data of 10 patients with idic (20q-) were analyzed. Karyotyping analysis was carried out with R banding technique. A CEP20 probe was used to perform single-color fluorescence in situ hybridization (FISH). A subtelomeric probe for 20q and a locus-specific probe for 20q12 were used to perform dual-color FISH. The literatures of hematologic malignancies with idic(20q-) were reviewed.
Results: Of the 10 cases, 2 were diagnosed as acute erythroid leukemia, 1 primary myelofibrosis, 3 myelodysplastic syndromes (MDS) and 4 highly suspected (HS-MDS). Karyotype analysis showed that one of the normal chromosome 20 allele was substituted by one or two metacentric isochromosomes smaller than the normal one in all 10 cases. It was confirmed to be der(20)del(20)(q11q13)idic(20)(p11), i.e., idic(20q-) by FISH assay. Partial cells in 2 of the 10 cases had 20q- as the sole karyotypic anomaly.
Conclusion: Idic(20q-) results from a pre-existing del(20q) and is strongly associated with MDS and acute erythroid leukemia. Idic(20q-) as a recurrent cytogenetic abnormality is helpful for diagnosing HS-MDS in patients with cytopenia but only slight or absent dysplasia.