What are the distinct cytogenetic abnormalities in DLBCL subtypes?

Updated: Jun 12, 2019
  • Author: Shipra Gandhi, MBBS; Chief Editor: Emmanuel C Besa, MD  more...
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Answer

Distinct cytogenetic abnormalities have been described in DLBCL patients. It is unclear to what degree such abnormalities contribute to the development or disease biology. Cytogenetic abnormalities vary between different DLBCL subtypes.

GCB-DLBCL

The most common translocation is t(14,18), with rearrangements of the BCL2 and IGH chain genes. [58] 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 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. [59] Another frequent aberration in the ABC group is trisomy 3. [60] 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.

Primary mediastinal lymphoma (PML)

Gain of the long arm of chromosome 9 is reported. [61] Duplication or multiplication of this locus is associated with up-regulation of the Janus kinase 2 (JAK2) gene. A gain of this gene is observed in 50% of the patients with PML. [62]


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