What is the t(14;18) Translocation in Follicular Lymphoma?

If you are looking at your pathology report and wondering what “t(14;18)” means, you are looking at the foundational genetic hallmark of follicular lymphoma. The t(14;18) translocation is a specific genetic mutation found in approximately 85% of people diagnosed with this condition ^[1][2]. It is not a mutation you inherited from your parents, but rather an acquired change in your B-cells (a type of white blood cell) that acts as the initial spark in the disease ^[1].

If your report does not show this mutation, do not panic. About 15% of follicular lymphomas develop through other genetic pathways, and the absence of t(14;18) does not mean your diagnosis is wrong or necessarily indicate a worse prognosis.

The “Genetic Swap”: What is a Translocation?

Inside every cell in your body, your DNA is packaged into structures called chromosomes. Humans typically have 23 pairs of chromosomes. A translocation happens when two chromosomes break and swap pieces with each other.

In the case of t(14;18), the “t” stands for translocation, and the numbers “14” and “18” tell us exactly where the swap occurred ^[2]. A piece of chromosome 14 trades places with a piece of chromosome 18. This might sound like a simple mix-up, but it brings two specific genes together that were never meant to be neighbors.

The BCL2 Protein: Switching Off Natural Cell Death

To understand why this swap causes follicular lymphoma, we have to look at the two genes that get forced together:

• The IGH Gene (Chromosome 14): In B-cells, the immunoglobulin heavy chain (IGH) gene is naturally highly active because it tells the cell to make antibodies to fight infections ^[1]. It is essentially stuck in the “on” position.
• The BCL2 Gene (Chromosome 18): This gene produces the BCL2 protein, which acts as an anti-death signal ^[1]. Normally, when cells become old, damaged, or are no longer needed, they undergo a natural, programmed cell suicide called apoptosis. BCL2 stops this process.

When the t(14;18) translocation occurs, the BCL2 gene is moved right next to the highly active IGH gene ^[1]. Because the IGH gene is always turned “on,” it forces the BCL2 gene to stay “on” as well ^[1].

This causes the cell to overproduce the BCL2 protein, which effectively blocks the cell’s natural ability to die ^[1]. Instead of living their normal lifespan and dying off to make room for new cells, these B-cells become somewhat “immortal” and slowly pile up in your lymph nodes ^[1]. This cellular pile-up is directly responsible for the swollen glands you may have noticed when you were first diagnosed.

Why Other Mutations Matter

While the t(14;18) translocation is the engine that drives the overproduction of BCL2, it is usually not enough on its own to cause follicular lymphoma to fully develop ^[3][4]. In fact, this specific translocation can sometimes be found in tiny amounts in healthy individuals without ever causing cancer ^[3].

For the disease to progress, the B-cells typically need to accumulate secondary genetic mutations ^[5][6]. These “second hits” often involve genes that control how the cell matures and interacts with your immune system, such as KMT2D, EZH2, or TNFRSF14 ^[7][8].

Pathologists primarily use the t(14;18) translocation to confirm your diagnosis, but secondary mutations are what increasingly guide specific treatment choices ^[1][9]. For example, mutations in the EZH2 gene occur in about 25% of follicular lymphoma patients and are now a direct target for certain newer therapies ^[8][10]. Understanding your complete genetic profile helps your doctors predict how your lymphoma might behave and choose the most effective treatments for you ^[9][7]. To get this complete profile, your care team may need to run an advanced test called Next-Generation Sequencing (NGS) on your biopsy sample, which you can ask them about during your next visit.