Leukemia is a cancer that affects the body’s bone marrow, where your blood cells are made. Leukemia is considered a gene-related disease, but usually is not hereditary — meaning, it generally can’t be inherited from parent to child.
Instead, most leukemias are linked to specific risk factors you have during your lifetime, some of which you can control and some that you can’t. A risk factor is a behavior, environmental influence, disease history, or characteristic like your age, race, or gender that make it more likely you will develop a disease or condition, although it is not the cause of the condition. You may have a particular risk factor, or several, and never develop the associated disease or condition.
Gene mutations can cause leukemia
A gene mutation in the DNA of your blood cells can cause certain types of leukemia. A mutation can produce blood cells that malfunction, and the number of malfunctioning blood cells in your system may eventually overwhelm the number of normal blood cells. Having too many mutated blood cells can also prevent your bone marrow from continuing to produce healthy blood cells.
When we say that this disease is genetic but not hereditary, it means that the mutations in your DNA that make you more susceptible were not handed down to you from a previous generation, but rather have been caused by other influences during your lifetime. These are called acquired gene mutations.
For instance, if, as a child, you are exposed to secondhand or thirdhand smoke or other pollution day after day, your cells may begin to develop mutations early in your life. If you become a smoker in your teens or young adulthood, or you develop obesity, you may experience changes or mutations in your DNA later in life. Radiation, plastics, and chemical contaminants in everyday life or on the job can also trigger mutations in DNA after years of exposure.
Acquired vs. inherited gene mutations
In contrast, inherited gene mutations are passed on by parents to their offspring during fertilization, either in the ovum from the mother or the sperm from the father. Children born with the inherited gene mutation will be at higher risk of certain cancers linked to that mutation. Most experts suggest that the vast majority of leukemias are not inherited.
What are risk factors for developing leukemia?
There are individual and overlapping risk factors for the four main types of leukemia — acute myeloid leukemia (AML), acute lymphocytic leukemia (ALL), chronic myeloid leukemia (CML), and chronic lymphocytic leukemia (CLL).
Risk factors for AML and ALL include certain genetic conditions, lifestyle habits, and blood disorders:
- Neurofibromatosis – a nervous system disorder that causes tumors to grow on nerves
- Fanconi anemia – a condition of bone marrow that results in decreased production of all types of blood cells
- Klinefelter syndrome – a set of symptoms such as infertility and small testicle size that occur in men who have two X chromosomes
- Bloom syndrome – a syndrome that is associated with short stature, higher cancer risk, and gene instability
- Ataxia-telangiectasia – a rare neurodegenerative disease that causes potentially severe disability
- Down syndrome – a common condition associated with developmental disabilities and other health problems that occurs when a person has an extra copy of chromosome 21
- The blood disorders primary thrombocytopenia, myelodysplasia, and polycythemia vera
Exposure to certain chemicals and pollutants raise the risk of leukemia. The key chemical implicated in AML is benzene. Professions or situations that increase exposure to benzene include working in:
- A chemical plant
- A gas station
- Shoe manufacturing
- The oil refinery business
- The rubber industry
Another chemical exposure linked to leukemia is Agent Orange, which was widely used during the Vietnam war.
Individuals who had previous radiation therapy or chemotherapy for another cancer are at increased risk of developing any of several types of leukemia later on.
In addition, children exposed to cytomegalovirus (CMV) have a higher risk of developing ALL later in life.