What is a PTEN genetic test?

A PTEN genetic test uses a sample of your blood or other body tissue to look for changes in a gene called PTEN. Changes in your genes are also called gene variants or mutations.

Genes are parts of DNA in your cells that you inherit from your parents. Genes carry information that controls what you look like and how your body works.

PTEN is a type of gene called a "tumor suppressor." Tumor suppressor genes provide instructions for making proteins that control how fast your cells grow and divide to make new cells. The proteins also help stop the growth of abnormal cells.

If you have changes in your PTEN gene, the gene or the protein it makes may not work well or may stop working completely. This can lead to serious health problems, including cancer. Changes in your PTEN gene can be acquired or inherited.

Acquired changes in your genes develop at some time after you're born. Acquired changes in the PTEN gene are commonly found in many different types of cancer, including prostate cancer, uterine cancer, and some types of brain tumors. Acquired changes in your PTEN gene:

• Can happen if your cells make a mistake when they divide to make new cells
• Can happen if you're exposed to substances that cause cancer
• Show up only in certain types of cells
• Usually aren't in sperm or egg cells, so they can't be passed down to children

Inherited changes in your genes are changes that you're born with. They show up in all the cells in your body, including your egg or sperm cells. That means they can be passed down to your children.

Inherited changes in the PTEN gene aren't common. But when they happen, they can cause several types of disorders. These disorders all include the growth of benign tumors (not cancer). These tumors are called hamartomas. The disorders are grouped together and called PTEN hamartoma tumor syndrome (PHTS). Cowden syndrome and Bannayan-Riley-Ruvalcaba syndrome are two types of PHTS disorders.

Hamartomas and other symptoms of PHTS can show up in infancy or later. PHTS increases your risk for certain types of cancer, but the cancer usually doesn't develop until adulthood.

Other names: PTEN gene, full gene analysis; PTEN sequencing and deletion/duplication, PTEN FISH, chromosome 10 deletion, CHR 10

What is it used for?

The PTEN genetic test is used to look for changes in your PTEN gene. It's not a routine test. It may be used to:

• Find out if a change in your PTEN gene is involved in cancer
• Check for inherited changes in your PTEN gene if you have:
  • Family members who have PTEN gene changes
  • Symptoms of PTEN hamartoma tumor syndrome (PHTS)

Why do I need a PTEN genetic test?

If you have cancer, you may need a PTEN genetic test to check whether your cancer cells have a PTEN gene change. Genetic changes in cancer can affect how the disease responds to treatment and how it may behave over time. So, your test results can help guide your treatment plan.

If you have a family history of PTEN gene changes and/or symptoms of PHTS, a PTEN genetic test can help you understand and manage your cancer risk. The test can also show whether you have a genetic change that you could pass on to your children.

You or your child may need a test if you have symptoms of PHTS, which include:

• Having many hamartomas, especially in the mouth, stomach, intestines, or skin
• A larger than normal head size (macrocephaly)
• Developmental delays, learning disabilities, and/or autism
• Dark freckles on the penis
• Thyroid, kidney, or colorectal cancer
• Uterine or breast cancer (in females only)

If you're pregnant and have a family history of PTEN gene changes, you may consider having the test as part of your prenatal testing. The test can show whether your baby could be born with PTEN hamartoma tumor syndrome.

What happens during a PTEN genetic test?

If you're having a PTEN genetic test because you have cancer, the type of sample used will depend on your cancer:

• For solid tumors, the test often uses a sample of tissue from the tumor. The tissue sample may be taken during surgery to remove the tumor. If you're not having surgery, you may have a biopsy of the tumor to remove a small amount of tissue.
• For blood or bone marrow cancer, a bone marrow test is often used. Marrow is soft, spongy tissue found inside of bones. Most bone marrow samples are taken from the back of the hip bone.

If you're having the test to look for inherited gene changes, you may have:

• A blood test. During a blood test, a health care professional will use a small needle to remove a blood sample from a vein in your arm.
• A buccal (cheek) swab. A health care professional will insert a swab into your mouth and rub it across the inside of your cheek to gather a sample of cells.

If you're testing an unborn baby, a sample may be gathered using:

• Amniocentesis. This procedure collects a sample of the amniotic fluid that surrounds the unborn baby during pregnancy. The fluid contains cells from the baby that can be tested. Amniocentesis is usually done between week 15 and 20 of pregnancy.
• Chorionic villus sampling (CVS). This procedure collects tissue from the chorionic villi, which are parts of the placenta. The placenta is the organ that grows in the uterus to provide nutrients and oxygen to the baby. The chorionic villi usually have the same genes as the unborn baby. A CVS is usually done between week 10 and 13 of pregnancy.

Will I need to do anything to prepare for the test?

If you're having a tissue biopsy or bone marrow test, ask your provider for instructions about how to prepare.

A blood test or cheek swab usually don't require any preparation.

For a CVS or amniocentesis, you may need to drink extra fluid and not urinate before your test so that your bladder is full.

Are there any risks to the test?

The risks of a biopsy depend on the type of biopsy you have. In general, you may have soreness, pain, or bleeding where the tissue was removed.

After a bone marrow test, you may feel stiff or sore where the sample was taken. This usually goes away in a few days. Serious risks are rare, but may include swelling, bleeding at the site, or fever.

A blood test has very little risk. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

A cheek swab has no risks.

During amniocentesis or CVS, you may feel mild stinging or cramping. Both procedures are safe, but they do have a slight risk of causing miscarriage. Talk with your provider about the risks and benefits of these tests.

What do the results mean?

If you have cancer and your test results show you have an acquired change in your PTEN gene, your provider can explain what it means for your treatment plan and future health.

If your test results show that you have certain inherited changes in your PTEN gene, it doesn't mean you have cancer. But your risk of cancer may be higher than most people. Your provider may discuss steps you can take to reduce your cancer risk, including:

• Having a yearly exam
• Having frequent cancer screening tests to help find cancer early when it may be easier to treat
• Making lifestyle changes, such as getting more exercise, eating healthy foods, and quitting smoking
• Taking medicine or having surgery (mastectomy) to reduce the risk of breast cancer
• Having surgery (hysterectomy) to reduce the risk of uterine cancer

For children, your provider may recommend a yearly exam that includes a skin check. Yearly thyroid ultrasound tests may begin at age seven. Your child may also need a checkup to see how their brain and nervous system are developing.

Learn more about laboratory tests, reference ranges, and understanding results.

Is there anything else I need to know about a PTEN genetic test?

If you're thinking about getting tested for an inherited change in your PTEN gene, it may help to talk with a genetic counselor. Genetic counselors are specially trained to help you understand the risks and benefits of testing for you and your family. This can help you make informed decisions.

If you've been diagnosed with an inherited change in your PTEN gene, a counselor can explain your risk for cancer. The counselor can also help you decide about testing your children and how to manage your risk over time.