Polymerase Chain Reaction for Detection of the t(14;18) Translocation in Lymphomas

The t(14;18) (q21;q32) translocation was originally identified as occurring in follicular low-grade non-Hodgkin’s lymphomas of B-cell origin in 1978 (1), and has been found in up to 85% of cases subsequently (2 –4 ). The translocation appears to arise at the pre-B-cell stage in the bone marrow when VDJ recombination usually occurs (5 ), so that the Bcl-2 gene on chromosome 18 is connected to the 5′ end of one of the six J_H segments of the immunoglobulin heavy chain locus on chromosome 14 (6 ). The result of this is the constitutional upregulation of Bcl -2 expression (7 , 8 ), which results in the suppression of apoptotic cell death among the population carrying the abnormality (9 ). It is suggested that this disrupts the normal process by which B-cell clones are eliminated during affinity maturation in germinal centers (10 ), thereby giving rise to an expanded B-lymphocyte pool in which further lymphomagenic events can supervene.