Interphase FISH does not improve the detection of DEL(5q) and DEL(20q) in myelodysplastic syndromes.

Cytogenetic abnormalities identified by conventional cytogenetics (CC) have important prognostic and therapeutic roles in myelodysplastic syndromes (MDS). Fluorescence in situ hybridization (FISH) complements CC since it is able to evaluate large numbers of interphase and metaphase nuclei. The question has been raised as to whether interphase FISH in addition to CC is able to imprive the level of detection of del(5q) and del(20q) in MDS. This study performed interphase FISH with 5q and 20q probes in a series of 158 MDS patients with a normal karyotype. No hidden del(5q) or del(20q) was detected. A review of the literature identified 20 patients (1.96%) of 1018 patients (including the current series) and 3 (0.91%) of 331 patients to have a del(5q) or del(20q). Therefore, interphase FISH adds little, if any, improvement to the probability of detecting these deletions. However, interphase FISH is recommended in patients with no cell growth or when fewer than 20 metaphases are available for CC analysis.