RESUMEN
Background: The nonrandom recurrence of chromosomal abnormalities in multiple myeloma (MM) raises the possibility that they play a role in the pathophysiology and development of the disease. Fluorescence in situ hybridization (FISH) can identify a high frequency of certain abnormalities without the need for the proliferative and infiltrative index of malignant plasma cells required for conventional cytogenetic analysis. In this study, we describe the association between clinico-biological characteristics and chromosomal abnormalities in 30 Moroccan patients. Methods: The analysis of cytogenetic data, conventional and molecular, of 30 cases of MM, obtained from our previously cytogenetic study, and correlation of the results with the clinico-biological data of these patients. Results: The bone marrow of 5 of 21 patients (23 %) contained a chromosomally abnormal clone, and all karyotypes were complicated (>3 abnormalities). Interphase FISH (iFISH) has detected aberrations in 14 out of 30 (46 %) of the total cases. The proportion of plasma cells in the bone marrow was higher in patients with chromosomal abnormalities (median 29 %) (p = 0.01917) than in patients without abnormalities (median 11 %). Although there was a difference in the median ß-2 microglobulin percentage (13.8 % versus 6.8 %), it was not statistically significant (p = 0.6818). We also, categorized patients into those with a complex clone and those with a sole abnormality. Patients with high bone marrow plasma cell rate (median 45 %) and high rate of ß-2 microglobulin (median 24 %) showed a complex karyotype and a higher iFISH detection rate than those with plasma cells count for (median 20 %) and ß-2 microglobulin count for (median 11 %) but without statistical significance (p = 0.4338 et p = 0.45 respectively). Furthermore, patients with aberrations had significantly shorter overall survival (100 % for 800 days versus 150 days only). Conclusion: Our research has shown that different subgroups of patients with MM can be classified based on the underlying genetic abnormalities. Chromosomal abnormalities (CA) may give the plasma cell a proliferative advantage, increasing the virulence of the disease and affecting overall survival.
RESUMEN
Cytogenetic and iFISH plays a major part in the diagnosis of the MM and have an important prognostic significance. 10-15% of patients with amyloidosis will also have multiple myeloma (MM). Few studies have addressed the clinical and cytogenetic features of patients with AL amyloidosis with concurrent multiple myeloma. This study of MM case in which we found a near tetraploid complex karyotype with the t(11;14) (q13;q32) abnormality in cytogenetic analysis and the presence of t(4;14) and del(17p) by iFISH, referred to several studies which showed the translocation t(11;14) as the most frequent abnormality in both AL amyloidosis and MM.
RESUMEN
BACKGROUND: Multiple myeloma (MM) is a disease characterized by heterogeneous clinical presentations as well as complex genetic and molecular abnormalities. In MM, cytogenetic analysis is a challenge because of the low proliferation of malignant plasma cells. Thus, interphase fluorescence in situ hybridization (FISH), performed on sorted plasma cells detected abnormalities independently of a proliferative and infiltrative index. The purpose of this study was to explore, for the first time, the cytogenetic and molecular genetics features in Moroccan patients with multiple myeloma referred exclusively to National Reference Laboratory and to determine their risk stratification based on these features. METHODS: We performed cytogenetic analysis on 93 MM cases, all patients were subjected to FISH analysis, among which 45 patients have benefited from both FISH analysis and standard karyotype. RESULTS: Karyotype was normal in 78% (35/45) while, it was complex with varied structural and numerical abnormalities in 22% (10/45) of all patients, among which Hyperdiploid karyotype was found in 9% (n = 4 cases) and nonhyperdiploid in 13% (n = 6 cases). The most common numerical abnormalities were gains of chromosomes 3, 5, 9, 15, and 19. Whole chromosome losses were also frequent, affecting chromosomes X, 3, 14, 16 and 22. FISH analysis detected abnormalities in 50% of cases. The translocation t(4;14) and dup (1q) were the most frequent types of anomalies (14% and 13% respectively), followed by (17p) deletion and 14q32/IGH translocations with an undetermined origin (12% each) then the (1p) deletion (4%). For the normal karyotypes, FISH revealed chromosome abnormalities in 46%. CONCLUSION: This study compares the results of cytogenetic analysis of chromosomal abnormalities in the Moroccan population with other countries. ½ patient showed at least one type of molecular genetic abnormalities. Therefore, the introducing of the cytogenetic analysis is obligatory in the diagnosis of multiple myeloma.
