Cancer is caused by changes in a cell’s genes. Occasionally, these gene changes are hereditary — that is, passed down within families, from parents to children. Researchers estimate that 1 out of 20 cases of leukemia may be hereditary, although that number is probably higher for childhood leukemia.
Learning more about the genetic causes of leukemia can help you better understand your family’s risk.
Genes are a part of the DNA found in all of your cells. Genes provide instructions that tell each cell what to do. Cells use genes to make proteins, which then go on to perform multiple different tasks. Genes and their resulting proteins determine how long a cell lives, determine when the cell will divide and make new cells, and control what jobs the cell performs in the body.
In general, each person has two copies of each gene, one copy from each parent.
Sometimes, genes become damaged and develop changes called mutations. Mutations are like typos that cause the cell to read the gene’s instructions incorrectly. Gene mutations can cause a cell to:
Usually, gene mutations don’t cause any noticeable effects. In some cases, however, mutations can cause diseases like cancer. Cells don’t typically become cancerous until many different gene mutations occur, one after another.
Specific types of genes can cause cancer when they are mutated. Oncogenes cause uncontrolled cell division and tumor formation. They develop when proto-oncogenes — genes that tell the cell when to grow — develop mutations that make them become more active.
Additionally, tumor suppressors are genes that help prevent cells from growing when they shouldn’t. Tumor suppressors lead to cancer when mutations take away their ability to work correctly.
Finally, mutations in genes involved in DNA repair can lead to cancer. DNA repair genes make proteins that are responsible for fixing mutations, but when they are turned off, mutations can build up within a cell.
Knowing which gene mutations are present within your cancer can help in several ways throughout its progression:
Leukemia develops from blood cells. When a blood cell becomes damaged and genetic abnormalities accumulate, it can become cancerous. The cell begins to quickly divide, and the new leukemic cells crowd out the normal, healthy blood cells.
Some genetic mutations are acquired over the course of a person’s life. These mutations may be caused by older age or by agents that cause cell damage, such as smoking, UV light, or chemicals like benzene. Cancer treatments like chemotherapy drugs and radiation therapy can also cause mutations. Acquired mutations are only found in specific cells.
Inherited genetic mutations are passed down from parent to child because they occur in an egg cell or sperm cell. Inherited mutations are present at birth and are seen in every cell within the body. A person born with inherited mutations may also pass down these mutations to their children. It is these inherited mutations that can lead to hereditary cases of cancer. In general, inherited mutations make up 5 percent to 20 percent of all cancers.
Most cases of leukemia are not caused by inherited mutations. The majority of people who have leukemia don’t have any family history of the disease, and their children will not be more likely to have leukemia. In some cases, however, leukemia can be passed down within families, due to certain genetic diseases or risk factors. Researchers are continuously discovering additional hereditary causes of leukemia.
Rarely, cancers can be caused by a familial cancer syndrome, in which a particular cancer-causing gene mutation is passed down through multiple generations. When familial cancer syndromes occur, they tend to cause many cases of cancer within a single family. Family members are more likely to develop cancer at a young age and to develop multiple different types of cancer.
One familial cancer syndrome that can lead to leukemia is Li-Fraumeni syndrome. This disease is usually caused by a mutation in a gene called TP53, a tumor suppressor gene. People with Li-Fraumeni syndrome have an increased risk of developing leukemia, as well as:
A parent with Li-Fraumeni syndrome has a 1 in 2 chance of passing on the gene mutation to each child.
Up until recently, experts believed that very few familial syndromes caused leukemia. However, several hereditary leukemia syndromes have been discovered in the past couple of years. Specialists now think that there are about 12 different syndromes caused by acquired gene mutations that can lead to blood cancers like:
A person with a hereditary leukemia syndrome has a 50 percent chance of passing the condition to their children. Additionally, first-degree relatives — parents, children, and siblings of the affected person — may also have a higher chance of being diagnosed with leukemia. Genetic counseling can help families learn more about their cancer risk. Family members who have not developed leukemia can be screened to see if they have any genetic mutations that may eventually lead to cancer.
Some diseases caused by inherited genetic mutations can increase a person’s risk of leukemia. One such condition is neurofibromatosis, caused by the NF1 gene. Neurofibromatosis causes multiple benign noncancerous tumors to form on the nerves. It can lead to a higher risk of juvenile myelomonocytic leukemia. Neurofibromatosis may also increase risk of other types of leukemia, such as ALL and AML.
Fanconi anemia can also increase a person’s risk of developing blood cancers such as MDS and AML. It can be caused by mutations in 16 different DNA repair genes. People with Fanconi anemia have low levels of red blood cells and a higher risk of developing several different types of cancers.
Down syndrome, also called trisomy 21, is a genetic disorder that also increases a person’s chance of developing both AML and ALL. However, Down syndrome is not considered to be an inherited disease.
Some immune system conditions are hereditary and can also increase a person’s risk of leukemia. These include:
People who have family members with leukemia may be more likely to develop this disease themselves, even if doctors can’t find a known inherited gene mutation. Children who have an identical twin with leukemia have a 20 percent chance of developing leukemia themselves. Additionally, siblings of children with leukemia have a slightly increased chance of developing the disease.
Recent research has found that if you are the parent, child, or sibling of someone with leukemia, your risk of leukemia is also elevated. Some of this increased risk could be due to environmental factors, but scientists believe that some of the risk is related to inherited mutations. Scientists don’t yet know all of the hereditary gene mutations that may contribute to leukemia.
There is no way to completely prevent leukemia. You can lower your risk of developing acquired mutations by avoiding things that can damage your genes. However, you can’t change the genes you were born with, so there isn’t any way to prevent inherited mutations or other genetic risk factors.
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