Molecular & Genetic Markers
CDKN2A/B homozygous deletion
CDKN2A/B homozygous deletion is the loss of both copies of tumor-suppressor genes that, in certain gliomas, raises the grade to 4.
In short: CDKN2A/B homozygous deletion
- It is the loss of both copies of the CDKN2A/B genes.
- These genes normally restrain cell division.
- Losing both copies allows more aggressive growth.
- In IDH-mutant astrocytoma and oligodendroglioma, it affects grade and outlook.
What it is
CDKN2A/B homozygous deletion is the loss of both copies ("homozygous") of the CDKN2A and CDKN2B genes, which normally help restrain cell division. In certain gliomas, this deletion signals more aggressive behavior and raises the assigned grade.
Understanding CDKN2A/B homozygous deletion
The CDKN2A/B genes act as brakes on cell division (tumor suppressors). When both copies are lost, the brakes are removed, allowing more aggressive growth. The 2021 classification recognized the importance of this marker: in an IDH-mutant astrocytoma, CDKN2A/B homozygous deletion raises the tumor to grade 4 (the highest grade), even if the appearance alone might suggest a lower grade. It also carries an unfavorable significance in oligodendrogliomas. This is an example of a molecular feature overriding appearance to determine grade and prognosis. Detecting it requires molecular testing. Understanding CDKN2A/B homozygous deletion clarifies a marker that can raise a glioma's grade and signal more aggressive behavior.
Why it matters
Understanding CDKN2A/B homozygous deletion helps patients and families see how a molecular marker can raise a tumor's grade — in IDH-mutant astrocytoma, this deletion defines grade 4 even when the appearance suggests otherwise.
Common questions
What is CDKN2A/B homozygous deletion?
The loss of both copies of these tumor-suppressor genes.
What do these genes do?
They normally restrain cell division.
Why does it matter?
In IDH-mutant astrocytoma, it raises the grade to 4.
Bottom line
CDKN2A/B homozygous deletion is the loss of both copies of tumor-suppressor genes that, in IDH-mutant astrocytoma, raises the grade to 4.
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