Cytogenetics of non-Hodgkin's lymphoma

In the non-Hodgkin's lymphoma (NHL), recurring cytogenetic abnormalities have been identified, and significant correlations among them and morphology, immunophenotyping, and parameters of clinical outcome have been recognized. The structural involvement of the 14q32 band is substantially more frequent than are other common abnormalities, which include del(6q), i(17q), +3, +7, +12, +18, and +21. Twenty-two recurring translocations have been identified. Almost three-fourths of all breakpoints in NHL occur at sites to which lineage-determining, transformation-related genes, or fragile sites have been mapped. Besides the well-known association of the t(14;18) (q32;q21) with the follicular histologies and t(8;14)(q24;q32) with small non-cleaved cell lymphoma, several other associations between recurring cytogenetic abnormalities and morphologic subtypes have been found. Similarly, several associations between cytogenetic abnormalities and the B or T immunophenotype have been delineated. Trisomy 3 or duplications of 3p predict a favorable clinical outcome; trisomy 2 or duplication 2p and abnormalities of chromosome 17 predict a poor prognosis. Common sequential changes include a (second) 14q32 break and abnormalities of chromosomes 1 and 2. Continuing work in these areas will serve to identify more clearly those regions of the genome important to transformation, differentiation, clinical aggressiveness, and progression in NHL.