Cytogenetic abnormalities correlate with clinico-biological characteristics in 30 Moroccan multiple myeloma patients

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.

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.

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).

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.