Molecular Cytogenetic Abnormalities In Multiple Myeloma Detected By FISH

ObjectivesTo determine the frequency of molecular cytogenetic abnormalities about 1q21 Amp/RB1 Del/D13S319 Del/p53 Del and IgH rearrangement in multiple myeloma, and the proportion of the cells carrying these mutationsTo assess the correlation of these cytogenetic and immunophenotype of multiple myelomaTo assess the correlation of these five kinds of molecular cytogenetic abnormalitiesTo investigate the role of these molecular cytogenetic changes in the pathogenesis of multiple myelomaTo anlyse prognostic value of these five kinds of molecular cytogenetic abnormalitiesMaterials and Methods1.20newly diagnosed patients from January 2004 to September 2008 with multiple myeloma(6 females,14 males,median age 54.5 years old,average age 6-84 years old) were studied.The diagnosis of multiple myeloma was according to Diagnostic Criteria and therapeutic effect of Hematology edited by Zhang Zhinan.According to the type of M-protein of the 20 patients,there were 5 cases of IgGλtype,7 cases of IgGκtype,4 cases of IgAλtype,lcases of IgAκtype, 1cases of IgDλtype,1cases of double monoclonal type(IgGκ&IgGλ),1cases of light chain typeλ.According to the International Staging System(ISS),3 patients were classified as StageⅠ,12 cases as StageⅡ,and 5 cases as StageⅢ. 8 patients with non-hematologic malignancies(5 males,3 females) between 45 and 67 years old were examined as controls.2.Probes:Rhodamine labeled sequence-specific DNA probe for 1q21,FITC labeled sequence-specific probe for P53 gene,FITC labeled sequence-specific probe for RB1 gene,Rhodamine labeled sequence-specific DNA probe for D13S319,FITC and Rhodamine dual-labeled sequence-specific DNA probe for IgH gene.The above-mentioned five kinds of probes are provided by China Medical Technologies, Inc.3.Chromosomes were made by direct and/or short-term culture method under sterile conditions from collection of bone marrow specimens from 20 newly diagnosed multiple myeloma patients without any prior cytoreductive therapy and 8 patients with non-hematologic malignancies4.Chromosomes from the 20 newly diagnosed patients and 8 patients with non-hematologic malignancies were detected with fluorescence in situ hybridization (FISH) using the above mentioned five kinds of probe.6.Data analysis using SPSS 16.0.Results1.Of the 20 patients,8 cases of 1q21 Amp was detected(40%),the median proportion of 1q21 Amp positive cells was 30%;5 cases of RB1 Del was detected (25%),the median proportion of RB1 Del positive cells was 40%;5 cases of D13S319 Del was detected(25%),the median proportion of RB1 Del positive cells was 40%;2 cases of p53 Del was detected(10%),the median proportion of RB1 Del positive cells was 21.5%;9 cases of IgH rearrangement was detected(45%),the median proportion of IgH rearrangement positive cells was 20%.No significant difference in the detection rate of the five kinds of molecular cytogenetic abnormalities was evident between our study and other international large-scale study previously reported(p＞0.05).2.Of the 8 1q21 Amp positive patients,there were 4 cases of IgG type,1 case of IgGλ/IgG double monoclonal type,2 cases of IgA type,1 case of IgD type;All the 5 RB1/D13S319 Del double positive patients were IgG type;Both of the two patients with p53 deletion were IgA type;Of the 9 patients with IgH rearrangement, 5 were IgG type and 4 were IgA type.3.Of the 8 1q21 Amp positive patients,5 cases were classified as ISS StageⅢ, 3 cases as ISS StageⅡ;Of the 5 RB1/D13S319 Del double positive patients,2 cases were classified as ISS StageⅢ,3 cases as ISS StageⅡ;Both of the two patients with p53 deletion were classified as ISS StageⅢ;Of the 9 cases with IgH rearrangement, 5 eases were classified as ISS StageⅢ,3 cases as ISS StageⅡ,1 cases as ISS StageⅠ.4.All the 5 RB1 Del positive patients also showed existence of D13S319 Del; both of the two patients with P53 deletion also showed 1q21 amplification /p53 deletion / IgH rearrangement positive.Conclusions1.1q21 amplification/RB1 deletion/D13S319 deletion/p53 deletion and IgH rearrangement are common molecular cytogenetic abnormalities in multiple myeloma.There were no statistically significant differences in the detection rate between this study and other international large-scale study.2.RB1 Del and D13S319 Del often co-exist in the same patients.3.The 2 patients with p53 deletion also showed 1q21 amplification/p53 deletion and IgH rearrangement positive,indicating that there may be some intrinsic association among the 3 types of molecular cytogenetic abnormalities.4.The 2 p53 positive patients were both ISS stageⅢ,indicating that p53 Del was associated with poor prognosis in patients with MM.The sample size was too small to perform a meaningful statistical test.To verify this hypothesis,an expanded sample size was required.