Comparison between Conventional Cytogenetics and Interphase Fluorescence in situ Hybridization (FISH) for Patients with Multiple Myeloma

Background: For patients with multiple myeloma (MM), different strategies are used to detect chromosomal abnormalities (CA). There have been a few studies that have directly compared FISH with conventional cytogenetics (CC) for the detection of CA. In this study, we employed a combined approach of metaphase cytogenetics and interphase FISH to investigate the genetic basis for the great heterogeneity observed in the clinical behavior of 28 MM patients. Methods: Cytogenetic analysis was performed via traditional metaphase karyotype analysis. The FISH studies were done using DNA probes to detect translocations involving the immunoglobulin heavy chain gene (IGH) at 14q32 and deletions of 17p13.1 and 13q14. Results: CA were detected by CC in 16 patients (57.1%) and by FISH in 14 patients (50.0%) of the 28 patients we studied. 14q32 abnormalities and deletion abnormalities of 13q14 and 17p13.1 were detected by CC in five patients (17.9%), three patients (10.7%) and no patients (0%), respectively and these were detected by FISH in 12 (42.8%), four (14.3%) and five (17.8%), respectively, of the 28 patients we studied. The median follow-up timefor the patients was 23.85 months (range: 0.3-58.13 months). On the univariate and multivariate analyses, none of the abnormalities detected by cytogenetics and interphase FISH affected survival. Conclusion: On comparing the cytogenetics and interphase FISH results, we can suggest that both studies should be an essential part of the workup for the diagnosis of patients with MM. Also, both studies may complement each other to predict the prognosis.