A rare genetic inherited autosomal dominant syndrome characterized by development of hamartomatous polyps throughout the gastrointestinal tract, and by changes in skin pigmentation. This disorder increases the risk of developing cancer. The prevalence of Peutz-Jeghers syndrome is estimated to range from 1/25,000 to 1/300,000 births.
The characteristic harmatomatous polyps generally occur in childhood and early adulthood during the first 10 years of life. Hamartomatous polyps can occur at any site in the gastrointestinal tract but are most frequent in the small intestine. Although benign, the polyps can cause complications including bowel obstruction, rectal prolapse, and severe GI bleeding with secondary anemia.
During childhood patients may develop dark blue to dark brown skin pigmentation changes around the mouth, eyes, nose, and in the perianal area. Hyperpigmentation may also be found on the fingers and toes.
Peutz-Jeghers syndrome is usually caused by mutations in the STK11 tumor suppressor gene which occurs in more than 80% of affected families increasing the risk of developing colorectal and gastric cancer in 15% of individuals by 50 years of age, and 57% by 70 years. There is also an increased risk of developing pancreatic breast and ovarian cancer in females as well as adenoma malignum of the cervix, and bilateral multifocal sex cord tumors with annular tubules.
Genetic counseling
Molecular genetic testing for the STK11 gene confirms the diagnosis. and is available clinically. The syndrome is inherited in an autosomal dominant manner. The number of cases related to de novo gene mutations is not known. Affected individuals should undergo genetic counseling informing them of the 50% risk of passing the mutation to their children.
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