Objective: To explore the clinical and laboratory characteristics of two myelodysplastic syndromes (MDS) patients with double isochromosome 20q- anomaly.
Methods: Bone marrow cell chromosome preparations were made with both direct method and short-term culture. Karyotype analysis was performed by R-banding technique, and dual-color FISH (fluorescence in situ hybridization) by using a 20q telomeric probe and a sequence-specific probe for 20q12.
Results: The clinical and hematological findings were comparable with diagnosis of MDS. Karyotype analysis showed that both patients had double isochromosome 20q- anomaly: case 1 is 46, XX, der(20)? i(20q-) [6]/46, idem, der (6) i (6p) [1]/47, idem, +der (20)? i (20q-) [3]/47, idem, der(6)i (6p), +der(20)? i (20q-) [20]; case 2 is 45, XY, -7, der (20)? i (20q-) [17]/46, idem, +der(20) ? i(20q-) [3]. Two derivative chromosomes 20 were proved 20q isochromosomes with interstitial deletions by dual-color FISH in one patient.
Conclusions: Double isochromosome 20q- anomaly is a rare recurrent karyotype abnormality in MDS, and signals a poor prognosis.