Rhabdoid Tumor Predisposition Syndrome

Rhabdoid tumor predisposition syndrome is a rare genetic disorder. It increases a person’s risk of developing a kind of fast-growing malignant tumor called a rhabdoid tumor. These tumors often grow in the brain, spinal cord, and kidney. They may also develop in the soft tissues, lungs, skin, and heart. These tumors are most common in children.

People with rhabdoid tumor predisposition syndrome also have a higher risk of developing non-cancerous tumors that grow along the nerves, called schwannomas. Schwannomas may cause painful lumps or tingling and numbness in some areas of the body. These tumors are more common in adults.

Not all people with rhabdoid tumors have rhabdoid tumor predisposition syndrome. When rhabdoid tumors develop in people without rhabdoid tumor predisposition syndrome, the tumors are called sporadic rhabdoid tumors. Only 30–35% of people (about 1 in 3) with rhabdoid tumors have rhabdoid tumor predisposition syndrome.

Cancer risk with rhabdoid tumor predisposition syndrome

People with rhabdoid tumor predisposition syndrome have a higher risk of developing rhabdoid tumors than people in the general population. This risk is highest in young childhood and decreases after age 5. Older children and adults with rhabdoid tumor predisposition syndrome may have an increased risk of developing schwannomas.

Although people with rhabdoid tumor predisposition syndrome are at higher risk for tumors, some people never develop them. Doctors do not understand why some people with rhabdoid tumor predisposition syndrome develop tumors and some do not. Researchers have only recently started studying this genetic disorder. Further studies may help doctors to better understand the risks.

Causes of rhabdoid tumor predisposition syndrome

Often this syndrome is caused by changes in a gene called SMARCB1 (also called INI1), or less commonly by changes in a gene called SMARCA4 (BRG1). When a gene change causes a disorder or disease, it is called a gene mutation. Genes carry information telling cells in the body how to function. The SMARCB1and SMARCA4 genes help to control how cells grow, divide, and die.

How rhabdoid tumor predisposition syndrome is inherited

Most people without rhabdoid tumor predisposition syndrome carry 2 working copies of the SMARCB1 or SMARCA4 gene in their cells. Cells from people with rhabdoid tumor predisposition syndrome carry 1 working copy of SMARCB1 or SMARCA4 and 1 mutated copy. 

A few children with rhabdoid tumor predisposition syndrome inherit their mutation from a parent who also has the syndrome. But most children have a new SMARCB1 or SMARCA4 mutation that did not come from a parent. These children have no history of the syndrome in their family. In these cases, the gene change either happened in an egg or sperm cell that formed the child. Or the changes happened in one of the child’s cells during pregnancy. These children are the first in their families to have rhabdoid tumor predisposition syndrome. 

No matter how children acquired the gene mutation, people with rhabdoid tumor predisposition syndrome have a 50% (or 1 in 2) chance of passing it on to their children.

Rhabdoid tumor predisposition syndrome diagnosis

Health history 

A health care provider may suspect that your child has rhabdoid tumor predisposition syndrome after studying their medical and family cancer history.

This information helps the health care provider and the genetic counselor know if:

• There are more cancers than normal in your family
• These cancers happened at a younger age than expected
• The cancers are those that are seen in rhabdoid tumor predisposition syndrome

Your provider or genetics counselor may recommend SMARCB1 or SMARCA4 genetic testing if they suspect this condition.

Learn more about genetic testing. 

Genetic testing for rhabdoid tumor predisposition syndrome 

A blood or tumor tissue sample is sent to a genetic testing lab. The lab runs genetic tests that look for changes in the SMARCB1 or SMARCA4 gene.

If your child has a SMARCB1 or SMARCA4 mutation, the genetic counselor will work with your family to:

• Find out if other family members should consider testing for a SMARCB1 or SMARCA4 mutation
• Help your family understand the increased cancer risk from rhabdoid tumor predisposition syndrome
• Give you information to help with your decisions about prenatal genetic testing

Genetic testing before or during pregnancy 

Parents may choose to do prenatal testing to find out if a pregnancy is affected with a known SMARCB1 or SMARCA4 mutation. Testing may take place either before pregnancy occurs or during pregnancy.

You should work with a genetic counselor to review the pros and cons of the test. The genetic counselor can also help you prepare for the test results.

Testing before pregnancy is called preimplantation genetic testing (PGT). This special type of genetic testing is done along with in vitro fertilization (IVF). PGT tests embryos for a known SMARCB1 or SMARCA4 mutation before a provider places the embryo into the uterus.

Testing during pregnancy can help providers see if a pregnancy has a known SMARCB1 or SMARCA4 mutation. A doctor gathers cells from the pregnancy in 1 of 2 ways:

• Chorionic villus sampling (CVS) is done during the first 3 months of pregnancy (1st trimester).
• Amniocentesis is done after the first 3 months of pregnancy (2nd trimester or later).

After tissue collection, the lab checks the sample for the SMARCB1 or SMARCA4 mutation.

Both tests carry minor risks. Discuss risks with an experienced health care provider or a genetic counselor.

Special concerns for genetic testing 

Take time to think carefully about the benefits and risks of genetic testing. Speak with a genetic counselor before testing. If you decide to get tested, talk with your health care provider or a genetic counselor about your results so you can understand what they mean. 

Sometimes, children or adults with rhabdoid tumor predisposition syndrome feel sad, anxious, or angry after getting their test results. Parents may feel guilty if they pass a SMARCB1 or SMARCA4 gene mutation to 1 or more of their children. People with a SMARCB1 or SMARCA4 gene mutation may also have trouble getting disability or life insurance. 

Read more about genetic discrimination. 

Monitoring and follow-up care for rhabdoid tumor predisposition syndrome

People with the syndrome should be monitored and have follow-up with a health care provider who knows the condition well.

Regular physical checkups and screenings are important. That way, any tumor that develops can be found early and at the most treatable stage.

Cancer screening for rhabdoid tumor predisposition syndrome 

Some health care providers recommend that people with this condition have a brain MRI exam and an abdominal ultrasound as soon as they are diagnosed, and then regularly after that. An MRI uses magnetic fields and radio waves to make images of the inside of the body. Ultrasound uses sound waves to make images of the inside of the body.

Screening recommendations may change as we learn more about this syndrome. This condition is rare and complex. People with the diagnosis should be cared for by an experienced health care team. 

Living with rhabdoid tumor predisposition syndrome

People of any age with rhabdoid tumor predisposition syndrome have a higher risk of cancer. They should monitor their health and adopt healthy habits.

Problems to watch for

Watch for signs and symptoms that could signal cancer:

• Unexplained weight loss
• Loss of appetite
• Aches, pains, lumps or swelling for no clear reason
• Headaches or changes in vision or nerve function that do not go away

It is important to seek medical help if anything unusual appears.

Maintain a healthy lifestyle

Habits that will help you maintain a healthy lifestyle include:

• A healthy diet with lots of fruit and vegetables.
• Regular exercise.
• Avoiding smoking or using tobacco products.
• Avoiding secondhand smoke.

Rhabdoid tumor predisposition syndrome care at St. Jude 

The St. Jude Cancer Predisposition Program is dedicated to diagnosing and screening children with a genetic predisposition for cancer. Our program offers the best clinical care possible. We engage in cutting-edge research to gain more information about genetic disorders and cancer, and to improve the care and treatment for patients who are affected by these conditions. Learn more about the Division of Cancer Predisposition at St. Jude.

Our genetic counselors, clinicians, genetics nurse practitioners, and research assistants work together to provide patients with:

• A complete health history
• A record of cancer that happened over the past 3 generations (family tree or pedigree) to see how diseases were passed down
• Physical exams to check for genetic disease
• Confidential genetic counseling and testing
• Cancer screenings for those with genetic disease to detect and treat cancer as soon as it occurs
• Recommended cancer treatments and ways to reduce cancer risk
• Genetic testing for immediate (1st degree) relatives

Rhabdoid tumor predisposition syndrome increases your child’s risk of cancer. 

Related clinical trials  

If you have questions about the Genetic Predisposition Clinic and care for rhabdoid tumor predisposition syndrome, email our team at GPTeam@stjude.org.

Resources outside St. Jude