Definition of FL subgroups with and without translocation t(14;18). 147 FLs showed evidence of the t(14;18) by PCR or FISH techniques, whereas 17 FLs were t(14;18)-negative. Within the t(14;18)-negative subgroup, 11 FLs were negative for BCL2 on the protein level, and 6 were positive, as determined by IHC.