The BCR-ABL1 genetic test is a crucial diagnostic tool used by healthcare professionals to detect an abnormal gene known as BCR-ABL1. This test involves analyzing a sample of blood or bone marrow to identify this specific genetic abnormality, which is strongly associated with certain types of blood cancers.
This abnormal BCR-ABL1 gene is not something you are born with; it arises from a genetic mutation. To understand its formation, it’s helpful to know a bit about our basic genetic structure. Our genes are segments of deoxyribonucleic acid (DNA), the fundamental building block of heredity. DNA contains the instructions that dictate our physical traits and bodily functions. This DNA is organized into structures called chromosomes within our cells. Typically, human cells contain 23 pairs of chromosomes, a standard genetic blueprint.
The BCR-ABL1 gene abnormality occurs when pieces of chromosome 9 and chromosome 22 break off and swap positions. Specifically, a fragment of chromosome 9, which includes a part of the ABL1 gene, breaks off and attaches (fuses) to a section of the BCR gene on chromosome 22. This fusion creates the abnormal BCR-ABL1 gene. The altered chromosome 22 is referred to as the “Philadelphia chromosome,” named after the city where it was first identified by researchers. This chromosomal change is a key indicator in certain leukemias.
Normally, genes provide instructions for creating proteins that are essential for cell function. However, the BCR-ABL1 fusion gene carries instructions for producing an abnormal protein. This protein disrupts the normal function of bone marrow cells, causing them to produce an excessive amount of abnormal white blood cells. These abnormal white blood cells are leukemic cells. Unlike healthy white blood cells, they are ineffective at fighting infections. Moreover, these leukemic cells can accumulate in the blood and bone marrow, crowding out healthy blood cells and leading to serious health complications.
Several types of BCR-ABL1 genetic tests are available to diagnose and monitor related conditions. These tests are designed to detect:
- The presence of the abnormal BCR-ABL1 fusion gene itself within blood or bone marrow samples.
- Chromosomal changes in chromosome 22, specifically looking for the Philadelphia chromosome as evidence of the BCR-ABL1 fusion.
It’s important to understand that an abnormal BCR-ABL1 gene is an acquired genetic change. This means it is not inherited from parents and cannot be passed on to offspring. Acquired genetic changes occur during a person’s lifetime, often due to errors in cell division as new cells are formed or from DNA damage caused by environmental factors. These genetic mutations are limited to specific cell types and are not present throughout the body from birth. Genetic changes are also commonly referred to as mutations or variants.
In summary, BCR-ABL diagnosis is critical in identifying specific types of blood cancers. The BCR-ABL1 genetic test is a vital tool for detecting the Philadelphia chromosome and the BCR-ABL1 fusion gene, enabling accurate diagnosis and informed treatment strategies for patients. Understanding this genetic abnormality is a key step in managing conditions like Chronic Myelogenous Leukemia (CML) and certain types of Acute Lymphoblastic Leukemia (ALL).
