Cytogenetic Study of 48 Patients with Multiple Myeloma and Related Disorders

We studied 48 patients with multiple myeloma and its related disorders (plasma cell dyscrasias: PCD). Clonal changes were observed in 19 patients (39.6%), which included 9 untreated and 10 treated patients. Chromosomal gains of 3, 11 and loss of 13 were the most frequent numerical chromosome aberrations. Chromosome 13 was lost at an early stage and 17p (p53) abnormality appeared in an advanced stage of the disease. The most common additional region was lq which contained a locus of the IL-6 receptor gene instead of 7p, the locus of the IL-6 gene. The break points were clustered at 1p13, 6q21, 7p11.2 14q32, 17p11 and 19p13.3, which were the loci of protooncogenes, tumor suppresser genes or immunoglobulin-related genes. Three patients showed a balanced translocation of t (11; 14) (q13; q32). The characteristic features of chromosomal changes in PCD were frequent chromosomal gains and losses and rare balanced translocations. These findings are similar to those found in secondary leukemias and solid tumors, rather than de novo leukemias.