t(14;19)(q32;q13) breakpoints telomeric to BCL3 on 19q13.32 in B-cell lymphomas other than chronic lymphocytic leukemia and long-range structures of der(19)t(14;19) based on optical genome mapping.

t(14;19)(q32;q13) is found in a fraction of chronic lymphocytic leukemia (CLL) patients and creates the IGH::BCL3 fusion gene, but this translocation has been observed in B-cell lymphomas other than CLL (non-CLL BLs). Ultra-high molecular weight DNA from liquid nitrogen-frozen leukemia cells of one CLL patient and OCT compound-embedded cryopreserved biopsies from two non-CLL BL patients, all of whom carried cytogenetic t(14;19), were subjected to optical genome mapping. In the CLL patient, t(14;19) resulted in fusion between IGHA1 and BCL3, whereas in the non-CLL BL patients, breakpoints on 19q13.32 involved NECTIN2 and BCAM as the IGH partners, both of which were located telomeric to BCL3. On der(19)t(14;19), chromosome 19 sequences centromeric to the breakpoints were fused to the germline IGHVs, or IGHV-D-J rearrangement sequences followed by the 5' Eµ enhancer and IGHM/IGHD constant genes. In the non-CLL BL patients, BCL3 was retained on der(19)t(14;19) and potentially affected by the translocated IGH.