Peutz-Jeghers syndrome (PJS) is an inherited condition that is associated with an increased risk of growths along the lining of the gastrointestinal tract (called hamartomatous polyps) and certain types of cancer. Most affected people also have characteristic dark blue to dark brown macules around the mouth, eyes, and nostrils; near the anus (perianal); and on the inside of the cheeks (buccal mucosa). PJS is caused by changes (mutations) in the STK11 gene and is inherited in an autosomal dominant manner. Management typically includes high-risk screening for associated polyps and cancers.

People with PJS also have a high lifetime risk of developing cancer. Cancers of the gastrointestinal tract (stomach, small intestine, and colon), breast, pancreas, cervix, ovary, uterus and lungs are among the most commonly reported tumors. Medscape reference offers more specific information regarding the risks for these cancers and the average age of onset. Please click here to view this resource.

Most affected people also have characteristic dark blue to dark brown macules around the mouth, eyes, and nostrils; near the anus (perianal); and on the inside of the cheeks (buccal mucosa). These spots may also occur on the hands and feet. They commonly appear during childhood and often fade as the person gets older.

STK11 gene. STK11 is a tumor suppressor gene which means that it encodes a protein that helps keep cells from growing and dividing too rapidly or in an uncontrolled way. Mutations in STK11 result in a defective protein that is unable to carry out its normal role. This leads to the development of the polyps and tumors found in PJS.

Some people with PJS do not have mutations in the STK11 gene. In these cases, the cause is unknown.

Peutz-Jeghers syndrome (PJS) is inherited in an autosomal dominant manner. This means that to be affected, a person only needs a change (mutation) in one copy of the responsible gene in each cell. In some cases, an affected person inherits the mutation from an affected parent. Other cases may result from new (de novo) mutations in the gene. These cases occur in people with no history of the disorder in their family. A person with PJS has a 50% chance with each pregnancy of passing along the altered gene to his or her child.

STK11 gene confirms the diagnosis in approximately 100% of people who have a positive family history and approximately 90% of people who have no family history of PJS.

GeneReviews offers more detailed information regarding the diagnosis of PJS including the clinical diagnostic criteria. Click here to view this resource.