Fluorescence in Situ Hybridization (FISH) Utility for Risk Score Assessment in MDS Patients with Normal Metaphase Karyotype

Abstract Background Cytogenetic profile is an essential parameter in MDS risk stratification by both IPSS and R-IPSS. Almost half of MDS patients have normal cytogenetics by metaphase karyotype. Here we report the yield of MDS FISH panel detecting cytogenetic abnormalities in these patients and its impact on risk stratification. Patient and Methods Among patients with normal metaphase karyotype, we assessed those patients who had cytogenetic abnormalities detected by an MDS FISH panel which included probes for (del (5), del (7), del (20), trisomy 8 and del (17p). Risk stratification was calculated by both IPSS and R-IPSS. Results Out of 1600 MDS patients with normal metaphase karyotype, 53 patients (3%) had cytogenetic abnormality detected by MDS FISH panel. Integrating the MDS FISH panel cytogenetics (IPSS + FISH restaging) resulted in upstaging the score where 53% of low risk IPSS were upstaged to int-1, 56% of int-1 upstaged to int-2, and 78% of int-2 upstaged to high risk. Based on the R-IPSS, 61% of very low risk patients, all low risk patients, 92% of intermediate risk patients, and 50% of high-risk patients with FISH abnormalities were upstaged respectively. Conclusion The yield of MDS FISH panel detecting cytogenetic abnormalities in patients with normal karyotype by G-banding is low and may not warrant ordering the panel in all patients. Among the 3% of patients with normal karyotype who had cytogenetic abnormality detected by FISH the risk score assignment by IPSS and R-IPSS was upstaged.