What are the distinct cytogenetic abnormalities in diffuse large B-cell lymphoma (DLBCL) subtypes?

Updated: Aug 20, 2020
  • Author: Shipra Gandhi, MBBS; Chief Editor: Emmanuel C Besa, MD  more...
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Answer

Distinct cytogenetic abnormalities have been described in different DLBCL subtypes. The ABC-DLBCL and GCB-DLBCL subtypes in the cell-of-origin (COO) classification have different genetic mutation landscapes, pathobiology, and responses to treatment. [24]

GCB-DLBCL

The most common translocation is t(14,18), with rearrangements of the BCL2 and IGH chain genes. [11]  Because of the increased expression of BCL2, the cells are immortalized. Increased BCL2 expression is associated with a poor prognosis and shorter survival. The second most frequent cytogenetic aberration in the GCB subgroup is translocation leading to rearrangement of the MYC gene. A recurrent change noted in a few patients is deletion of the tumour suppressor gene PTEN.

ABC-DLBCL

The most common aberration in ABC-DLBCL is translocation involving the BCL6 gene. [12]  Another frequent aberration in the ABC group is trisomy 3. [13]  Approximately 18 % of the patients diagnosed with ABC-DLBCL are diagnosed to have a deletion of the tumor suppressor gene P53. Inactivation of P53 results in uncontrolled cell proliferation and subsequent tumor genome instability. Mutations or deletions of P53 decrease the overall survival of all DLBCL patients.


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