Peutz-Jeghers Syndrome is a genetic condition that causes non-cancerous growths to develop in the digestive system. The growths, called hamartomatous polyps, usually grow in the small intestine. They can also grow in the stomach or large intestine. Sometimes they grow outside the digestive system and may appear in the kidneys, lungs, gall bladder, nasal passages, bladder, or the tubes that connect the kidneys to the bladder (ureters).
People with Peutz-Jeghers Syndrome often also have small, dark-colored spots that look like freckles on some parts of their skin. The spots usually appear during childhood and often fade as the person gets older. Most spots are on the lips, around and inside the mouth, near the eyes and nostrils, and around the anus. The spots may also occur on the hands and feet.
Having Peutz-Jeghers Syndrome increases a person’s risk of developing the following types of cancers:
- Digestive system cancer (stomach, esophagus, small intestine, pancreas, colon, or rectum)
- Breast cancer (females)
- Uterine cancer (females)
- A rare type of cervical cancer (females)
- Lung cancer
- Tumors of the ovaries and testicles (can be cancerous or non-cancerous)
Because Peutz-Jeghers Syndrome is hereditary, the condition can be passed from parents to children in a family. Peutz-Jeghers Syndrome often varies in how severe it is, even among people in the same family. Some people may have many polyps and may develop cancer at a young age, while others may only develop a few polyps and may not develop cancer.
Peutz-Jeghers Syndrome is caused by changes in a gene known as STK11. Genes carry information telling cells in the body how to work. The STK11 gene is needed for cells to grow and divide properly.
Most people without Peutz-Jeghers Syndrome carry two working copies of the STK11 gene in their cells. One copy is inherited from each parent. Cells from people with Peutz-Jeghers Syndrome carry one working copy of the STK11 gene in their cells and one copy that is changed. This change causes the STK11 gene to not work right. It is called a variant.
About half of children with Peutz-Jeghers Syndrome have inherited the STK11 gene variant from a parent. The other half of the children with Peutz-Jeghers Syndrome are the first people in their families to have a STK11 gene variant. These children have no history of the condition in their families. In these cases, the change either happened in an egg or sperm cell when the child was formed or in one of the child’s cells during pregnancy. These children are the first in their families to have Peutz-Jeghers Syndrome.
No matter how they acquired the variant, people with Peutz-Jeghers Syndrome have a 50% (1 in 2) chance of passing it on to their children.
A doctor may suspect this diagnosis based on physical exam and/or after looking at a person’s medical or family history. In most cases, a doctor or genetic counselor will ask questions about the person’s health and the health of other family members. Read more about genetic counseling and genetic testing.
Diagnosing this syndrome is usually done by sequencing the STK11 gene to find variants (gene changes).
The cancer risk in people with Peutz-Jeghers Syndrome increases with age, with about 1–2% risk by 20 years old, more than 30% by 50 years, and more than 80% by 70 years.
The lifetime risks for each type of cancer are:
- Breast: 32-54% (in females)
- Colorectal: 39%
- Pancreatic: 11-36%
- Stomach: 29%
- Ovarian: 21%
- Lung: 7-17%
- Cervical (adenoma malignum): 10%
Other types of cancers have also been reported in people with Peutz-Jeghers Syndrome.
Cancer screening involves tests to check for cancer before symptoms occur. The goal is to find cancer at the earliest and most treatable stage. Guidelines for cancer screening are available online. Recommended screenings may change over time as doctors learn more about this syndrome, so these screening tests should be discussed with a health care provider who knows this syndrome well.
Other ideas to reduce the risk of cancer include:
- Eat a healthful 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, hat, and protective clothing when out in the sun
- Get medical attention for unusual or ongoing symptoms
People with Peutz-Jeghers Syndrome may have some of the following medical issues. Not all people with Peutz-Jeghers Syndrome will have all of these issues.
The growth of polyps in the digestive system may cause the following:
- Bowel obstruction (blockage in the large or small intestine)
- Rectal prolapse (the wall of the rectum slides out of place, sometimes sticking out of the anus)
- Severe bleeding in the digestive system
- Anemia (too little oxygen in the blood), causing the person to feel tired
Tumors of the ovaries and testicles may cause the following:
- Puberty that happens at an unusually young age
- Irregular or heavy menstrual periods in women
- Growth of breasts in boys
- Unusually short height in boys
Because of the medical concerns related to this syndrome, specialists in the following areas may need to assess a child with Peutz-Jeghers Syndrome:
- Gastroenterology
- Gynecology
- Endocrinology
Resources about Peutz-Jeghers Syndrome:
- National Organization for Rare Disorders – Peutz-Jeghers Syndrome (https://rarediseases.org/rare-diseases/peutz-jeghers-syndrome/)
Other resources:
- Making Sense of Your Genes: A Guide to Genetic Counseling (www.ncbi.nlm.nih.gov/books/NBK115508/)
Adapted from educational materials developed by the St. Jude Children’s Research Hospital Cancer Predisposition Program