[The cytogenetic and molecular genetic study of 81 multiple myeloma patients]

To explore the cytogenetic characteristics of multiple myeloma (MM) patients, to evaluate the effect of a long-term culture stimulated by cytokines on cytogenetic study of MM, and to investigate the clinical detection value of RB1 and P53 deletion in interphase plasma cells by using fluorescence in situ hybridization (FISH).

Karyotype analysis was performed in 81 MM patients by using the short-term culture of bone marrow cell and G-banding technique. Among the 81 MM patients, 28 patients used two culture methods: one was the short-term culture and the other was to culture cells for 6 days with recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF) (40 µg/L) and IL-6 (10 µg/L). RB1 and P53 deletion were detected on interphase plasma cells by using FISH in 31 patients.

Among the 81 patients, 75 had enough metaphases for analysis. Among the 75 patients, 31 (41.3%) had clonal karyotypic abnormalities including 4 numeric abnormalities, 11 structural abnormalities and 16 both abnormalities. Among the 28 patients using two culture methods, the clonal karyotypic abnormalities were detected in 6 patients (25.0%) in the group of cultured for 24 hours, and 14 patients (51.9%) in 6-day culture group with a significant difference (P = 0.026). RB1 deletion and P53 deletion were detected in 10 patients (32.3%) and 11 patients (35.5%), respectively, with both RB1 and P53 deletions be detected in 5 patients (16.1%).

More than half of the tested MM patients have both numeric and structural chromosome abnormalities. The karyotype analysis using banding technique is basic cytogenetic study. Extended culture in the presence of IL-6 and GM-CSF could improve the efficiency of cytogenetic analysis to MM. Interphase FISH is a sensitive method of clinical application significance to detect the gene deletion of MM.