DICER1 Syndrome

DICER1 syndrome is a genetic disorder that makes a person more likely to develop certain types of tumors. The tumors can be both benign (non-cancerous) and malignant (cancerous). Not everyone with DICER1 syndrome will develop a tumor.

Children with this syndrome can develop 1 or more tumors in these areas:

• Lungs
• Ovaries
• Thyroid gland
• Kidneys
• Brain (pineal and pituitary glands)
• Other

In babies and young children with DICER1 syndrome, the most common type of tumor appears in the lung. It is known as pleuropulmonary blastoma (PPB).

Cancer risk with DICER1 syndrome

Children and young people with DICER1 syndrome have an increased risk of developing:

• PPB, a rare type of lung tumor usually occurring before age 6
• Ovarian sex-cord stromal tumors, such as Sertoli-Leydig cell tumor
• A rare and non-cancerous kidney tumor known as cystic nephroma
• An enlarged thyroid gland that contains growths known as nodules as well as thyroid cancer
• A tumor of the eye known as ciliary body medulloepithelioma
• A type of muscle cancer known as rhabdomyosarcoma (specifically, botryoid-type embryonal)
• A type of nose tumor known as nasal chondromesenchymal hamartoma
• Brain tumors known as pineoblastoma and pituitary blastoma

The exact risks for developing these or other tumors in DICER1 syndrome are not known.

Causes of DICER1 syndrome 

DICER1 syndrome is caused by changes in a gene known as DICER1. Genes carry important information that tells our body’s cells how to function. In ways that are not well understood, DICER1 aids in preventing tumors.

How DICER1 syndrome is inherited

Most cells of the body carry 2 working copies of the DICER1 gene in their cells. One is inherited from the mother and 1 from the father. Cells from people with DICER1 syndrome carry 1 working DICER1 gene copy and 1 copy that is altered. This change causes the gene to not work properly and is called a mutation.

Most people with DICER1 syndrome inherit it from a parent who also has the syndrome. But some people with DICER1 syndrome may have a new DICER1 gene mutation (change) that did not come from a parent. In these cases, the DICER1 mutation is new in these people, and they are the first in their families to have DICER1 syndrome.

No matter how it comes about, everyone with DICER1 syndrome has up to a 50% (1 in 2) chance of passing it on to their children.

Over time, the working copy of DICER1 can change within some of the cells. When both copies of the gene are changed, DICER1 tumors can develop. That is why people with DICER1 syndrome have a higher risk of developing 1 or more tumors.

DICER1 syndrome diagnosis

Health history

A health care provider may suspect that your child has DICER1 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 DICER1 syndrome

Your provider or genetics counselor may suggest DICER1 genetic testing if they suspect DICER1 syndrome. Learn more about types of genetic tests.

Genetic testing for DICER1 syndrome

A blood sample is sent to a genetic testing lab. The lab runs genetic tests that look for changes in the DICER1 gene.

If your child has a DICER1 mutation, a genetic counselor will:

• Find out if other family members should consider testing for a DICER1 mutation
• Help your family understand the increased cancer risk from DICER1 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 DICER1 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 DICER1 mutation before a provider places the embryo into the uterus.

Testing during pregnancy can help providers see if a pregnancy has a known DICER1 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 DICER1 mutation. Both tests carry minor risks. Discuss the 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 DICER1 syndrome feel sad, anxious, or angry after getting their test results. Parents may feel guilty if they pass the DICER1 gene mutation to 1 or more of their children.

People with a DICER1 gene mutation may also have trouble getting disability or life insurance. Read more about genetic discrimination.

Monitoring and follow-up care for DICER1 syndrome

There is no treatment for DICER1 syndrome. Instead, people with the syndrome should be monitored and have follow-up with a doctor who knows the condition well.

Children with DICER1 syndrome need regular screenings to detect tumors as early as possible. The goal of screening is to find and treat tumors early for the best outcome. Recommended screenings may change over time as doctors learn more about DICER1 syndrome.

Screening tests may include:

• Full physical exams
• Chest imaging
• Kidney ultrasound
• Thyroid exam
• Eye exam
• Brain MRI
• Pelvic ultrasound (for females)
• Gynecological exam (for females)

People with DICER1 syndrome should watch closely for signs and symptoms that could signal cancer. Seek medical help if anything unusual appears.

Living with DICER1 syndrome

Children with DICER1 syndrome have a higher risk of cancer. They should monitor their health and adopt healthy habits. It is important to continue to have regular physical checkups and screenings. That way, any cancer can be found early at the most treatable stage.

Problems to watch for

People with DICER1 syndrome should watch closely for general signs and symptoms that could signal cancer:

• Unexplained weight loss
• Loss of appetite
• Pain in abdomen (belly)
• Blood in the stool or changes in bowel habits
• Aches, pains, lumps, or swelling that cannot be explained
• Headaches or changes in vision or nerve function that do not go away

Seek medical help if anything unusual appears.

Maintain a healthy lifestyle

Habits that will help you maintain a healthy lifestyle include:

• Eat a healthy diet with lots of fruits and vegetables
• Get regular exercise
• Avoid smoking or using tobacco products
• Avoid secondhand smoke
• Avoid excess sun exposure and always wear sunscreen, a hat, and protective clothing when out in the sun

DICER1 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 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
  

DICER1 syndrome increases your child’s risk for many types of cancer. 

If you have questions about the Genetic Predisposition Clinic and care for DICER1 syndrome, email our team at GPTeam@stjude.org.

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