[Cytogenetics on malignant lymphoma]

Translocations involving band q32 on chromosome 14 are commonly identified as a 14q + marker-chromosome and the involvement is the single most frequent abnormality in various types of lymphoid cancer. Based on these findings, we have proposed that the 14q + marker-positive lymphoid cancer should be divided into subclasses according to the precise translocations, each of which is a primary chromosome change, and the subclass initiates serial processing of the karyotype evolution associated with the development of more aggressive lymphoid cancer. The proposal is strongly supported by recent advances in molecular genetics. Genes or unknown DNA sequences, which had evolutionally been conserved, were isolated from the breakpoint on the partner chromosome of the 14q+ translocation, and the DNA sequences identified to juxtapose to the IgH gene locus on chromosome 14 band q32 accompanied by individual translocation. Thus, we can subclassify the lymphoid cancers marked with chromosome changes involving the loci of other functional genes.