[Clinical and biological characteristics multiple myeloma with 1q21 amplification]

To study the clinical features of multiple myeloma (MM) patients with 1q21 amplification and the detection and biological characteristics of 1q21 copy number variation among different stages of plasma cell dyscrasias.

We analyzed the amplification and copy number variation of 1q21 in a cohort of 397 MM patients (290 newly diagnosed patients and 107 relapsed/refractory patients) in Institute of Hematology and Blood Diseases Hospital in the period between January 2009 and December 2012, using fluorescence in situ hybridization (FISH). We compared the incidence and biological characteristics of 1q21 gains among different stages of MM.

Among the newly diagnosed MM patients, the cases without 1q21 gains (148 cases) had difference prevalence of q13 deletion (38.3% (56/146) vs 57.7% (82/142), P=0.001), t(4; 14) translocation (17.4% (25/144) vs 30.7% (42/137), P=0.009), and high-risk cytogenetic abnormalities (28.3% (39/138) vs 41.9% (57/136), P=0.018), and International Staging System (ISS) stage (P=0.010) compared to those with 1q21 gains (142 cases); however, there were no significant differences in age(P=0.448), Durie-Salmon clinical stage (P=0.352) and β2-microglobulin level (P=0.414). In the newly diagnosed patients, the incidence of this 1q21 aberration with the percentages of plasma cells involved being ≥10%, ≥20%, and ≥30% was 52.4% (152/290), 49.0% (142/290), and 46.2% (134/290), respectively, lower than that in the relapsed/refractory patients (71.0% (76/107), P=0.001; 68.2% (73/107), P=0.001; 63.6% (68/107), P=0.002). Differences were found between the newly diagnosed MM patients and the relapsed/refractory ones in terms of the incidence of 1q21 copy number gains being 2 (52.2% (145/278) vs 33.3% (34/102), P=0.001), but not in the incidence of 1q21 copy number gains being 3, 4, and >5 (all P>0.05).

Amplification of chromosome 1q21 is a common genetic abnormality in MM patients. The copy number varies in patients carrying 1q21 gains, mainly with two or more copies of 1q21. It may therefore be recommended to include testing for 1q21 gains in routine genetic testing of MM patients.