Leukemia is a type of blood cancer, and there are many types and subtypes depending on the cells involved and the course of the disease. When we talk about T-Cell Acute Lymphoblastic Leukemia, also known as T-ALL, we are referring to a type of leukemia or blood cancer with the following characteristics:
- It involves T-cell lymphocytes, a variety of white blood cell that defends the body against bacterial infection
- It is acute, which mean it progresses very quickly and is potentially dangerous and aggressive
T-ALL shares many features of other types of leukemia, but has critical elements that allow us to identify and target T lymphocytes in the management of the disease.
What causes T-ALL?
Similar to other types of cancer, patients with T-Cell Acute lymphoblastic leukemia typically display a series of genetic alterations in cancer cells and stem cells in the bone marrow. Many types of genetic aberrations are known to cause T-ALL. For example:
- Genetic lesions of the T-cell receptor: Around 35% of patients have a lesion in the T-cell receptor, which is vital to promote T-cell differentiation, and to regulate the production of these cells. The aberration is usually located in the chromosome 7 and 14.
- Oncogene lesions: Oncogenes are normal genes in the body that turn cells into cancer when they become aberrant. The most common oncogenes that become activated in T-Cell Acute lymphoblastic leukemia are Notch1 mutations, HOXA cluster alterations, and other genetic abnormalities in TLX and TAL genes. In the majority of patients, these genetic alterations are associated with other disturbances, and they altogether cause T-ALL.
- Tyrosine kinase genetic lesions: These enzymes work as a second messenger in the body, and the aberration creates abnormal signals that cause cancer. Typical examples include the ABL1 gene, which is typically found in chronic myeloid leukemia, and JAK1 mutations, found in 18% of patients, and associated with a bad prognostic.
The most important risk factors in T-ALL include age and gender. This type of alteration is more common in children than adults, and the incidence is higher before 5 years of age. T-ALL affects a higher proportion of males than females, and even though the causes are genetic alterations, it is not an inherited disease. It is surely not contagious, either.