B-lymphoid neoplasms: immunoglobulin genes as molecular determinants of clonality, lineage, differentiation, and translocation.

The basic rules of Ig gene recombination that were learned from examining clonal proliferations of B cells have paid enormous dividends in improving our understanding of B-cell malignancy. The DNA rearrangements of Ig genes creates a tumor-specific marker capable of establishing the clonality, cellular lineage, and stage of development of a lymphoid tumor. Most importantly, the Ig genes have proved to be the sites of interchromosomal translocations that contribute directly to the malignant phenotype. These genetic tools hold the promise of improving our classification schemes, providing sensitive and specific approaches to following the clinical course, and providing insights into pathogenesis that will prompt improved therapies.