Peutz-Jeghers syndrome (PJS) is a genetic disorder that primarily affects the gastrointestinal tract, causing the formation of benign polyps called hamartomas in the intestines and stomach. It also causes the appearance of flat, discolored spots called macules, most commonly found on the lips, the inside of the mouth, and on the hands and feet. The polyps are not themselves cancerous, but people suffering from Peutz-Jeghers syndrome have a significantly elevated risk of cancer in many organs. It can also cause problems in the digestive system, including intestinal obstruction and abdominal pain. It is also sometimes called hereditary intestinal polyposis syndrome.
Peutz-Jeghers syndrome is believed to be caused by the mutation of a gene or genes responsible for the production of enzymes that regulate cell division and suppress the formation of tumors, though the mechanism is still not fully understood. Most, but not all, people with the condition have a mutation in the serine/threonine kinase 1, or STK11, gene located on chromosome 19. Many different mutations of the STK11 gene are possible, and the nature and severity of the symptoms of PJS can vary from one sufferer to the next as a result. The cause of the disease in people without a STK11 mutation is still unknown.
Peutz-Jeghers syndrome is autosomal dominant, meaning that the mutation that causes it is not on one of the sex-linked chromosomes (X and Y) and that one copy of the defective gene, received from either parent, is enough to cause the disorder. The genetic defect can also arise in someone with no family history of PJS, due to a new mutation rather than heredity. It is a rare condition, with estimates of its frequency ranging from one in 30,000 people to one in 300,000 people.
The first sign of Peutz-Jeghers syndrome is usually the appearance of brown macules on the skin in infancy, followed by the formation of macules in and around the sufferer's mouth. These often begin to diminish over time and may be gone by adulthood. Polyps begin forming inside the gastrointestinal tract during childhood, which can cause intestinal obstruction due to either blockage by the polyps themselves or by causing one part of the intestine to fold in on another part, a condition called intussuception. This obstruction can cause severe pain, vomiting, and bleeding, and if not treated can result in necrosis of intestinal tissue, sepsis, and eventually death.
People with Peutz-Jeghers syndrome have a dramatically increased risk of cancer. The risk of cancer is increased in numerous organs, appearing frequently in the pancreas, lungs, and the organs of the digestive tract. Women with the condition also have a higher risk of breast, uterine, and ovarian cancer.