National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Peutz-Jeghers syndrome

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I have many dark colored spots on my lips, inside my cheek, and on my gum. These spots developed while I was in my thirties. Although I do not have gastrointestinal symptoms and my family history is negative, my dermatologist has suggested the possibility of Peutz-Jeghers syndrome (PJS). I am concerned about the high incidence of cancer in PJS patients and would like to know if definitive testing is available.

The following information may help to address your question:


What causes Peutz-Jeghers syndrome?

Peutz-Jeghers syndrome (PJS) is caused by changes (mutations) in the 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.[1]

Some people with PJS do not have mutations in the STK11 gene. In these cases, the cause is unknown.[1]
Last updated: 3/15/2015

How is Peutz-Jeghers syndrome diagnosed?

A diagnosis of Peutz-Jeghers syndrome (PJS) is based on the presence of characteristic signs and symptoms. In people with a clinical diagnosis of PJS, genetic testing of the 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.[2]

GeneReviews offers more detailed information regarding the diagnosis of PJS including the clinical diagnostic criteria. Click here to view this resource.
Last updated: 3/15/2015

How can I find a genetics professional in my area?

To find a medical professional who specializes in genetics, you can ask your doctor for a referral or you can search for one yourself. Online directories are provided by the American College of Medical Genetics and the National Society of Genetic Counselors. If you need additional help, contact a GARD Information Specialist. You can also learn more about genetic consultations from Genetics Home Reference.
Last updated: 12/6/2017

We hope this information is helpful. We strongly recommend you discuss this information with your doctor. If you still have questions, please contact us.

Warm regards,
GARD Information Specialist

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  1. Peutz-Jeghers syndrome. Genetics Home Reference. February 2013; http://ghr.nlm.nih.gov/condition/peutz-jeghers-syndrome.
  2. Thomas J McGarrity, MD, Christopher I Amos, PhD, Marsha L Frazier, PhD, and Chongjuan Wei, PhD. Peutz-Jeghers Syndrome. GeneReviews. July 2013; http://www.ncbi.nlm.nih.gov/books/NBK1266/.