Karyotypic abnormalities and clinical aspects of patients with multiple myeloma and related paraproteinemic disorders.

Karyotypic abnormalities were detected in the malignant cells of 6 of 18 patients with multiple myeloma (MM). Six patients with benign monoclonal gammopathy, one with amyloidosis of immunoglobulin origin, and two with Waldenström's macroglobulinemia had normal karyotypes. All six MM patients with aneuploidy were in a group of 10 patients in an accelerated or relapse phase of their disease and four had high serum paraprotein levels (7.92, 6.24, 6.80, and 4.24 g/dl, respectively) when their abnormal karyotypes were detected. Five of the 6 MM patients with aneuploidy had received prior chemotherapy. Aneuploidy was not observed in 8 stable MM patients. Abnormalities of chromosome 14 were present in all 6 patients, with a 14q+ marker in 5 and loss of No. 14 in 1. A translocation between Nos. 11 and 14 was found in aneuploid cells of 2 patients who had plasma cell leukemia (PCL). However, the break point in the long arm of No. 11 differed in the 2 patients. A gain of Nos. 5, 9, and 11 was seen in 3 patients, a gain of No 1 in 2, and rearrangements of No. 1 in 5 MM patients, including all 4 who had a 14q+ marker chromosome initially. A deletion of chromosome 6 at band q25 was detected in 2 MM patients and a pericentric inversion of No. 6 (6p21 to 6q13) was seen in the patient with PCL. Three of 4 MM patients had a nonrandom loss of one chromosome 8. Two other MM patients, who were treated with melphalan and prednisone, developed acute nonlymphocytic leukemia (ANLL) 2+ and 4+ years after the diagnosis of MM. Marrow cells of one patient showed a 5q- chromosome and a constitutional translocation involving Nos. 13 and 14 during the preleukemic stage; during the leukemic phase, the karyotype evolved to 50 chromosomes including extra chromosomes 1, 6, 8, 10, and 21 and a missing 7, in addition to the originally detected 5q- and the 13/14 translocation. The peripheral blood from the other patient was hypodiploid, with a missing chromosome 7 and a translocation between 3q and 9p. These patterns of chromosome change resemble those of ANLL rather than MM and are similar to the changes seen in ANLL after treated malignant lymphoma.