Abstract: Follicular lymphoma ( FL ) is a low-grade B-cell non-Hodgkin's lymphoma of germinal center origin. The genetic hallmark of FL is the chromosomal translocation between the immunoglobulin heavy-chain gene on chromosome 18 and the Bcl-2 gene on chromosome 14. The resultant t ( 14;18 ) ( q32;q21 ) leads to the constitutive overexpression of Bcl-2 protein. Functionally, this phenomenon results in the prolongation of cell survival and lymphomagenesis. However, the translocation of t ( 14;18 ) is not present in all FL cases. Approximately 90% of all FLs carry this characteristic alteration; in the remaining cases, t ( 14; 18 ) is not detectable. The presence or absence of t ( 14; 18 ) is closely linked to the occurrence and development of FLs.