Peutz-Jeghers syndrome (PJS)
PJS is a rare condition, affecting about 1 in 200,000 persons. The classic presentation of this condition is development of mucocutaneous hyperpigmentation in childhood, and hamartomatous polyps of the gastrointestinal tract that can cause intussusception and bleeding. The median age of GI symptoms is 10 years. PJS is also associated with an elevated risk for cancers of the esophagus, stomach, small intestine, colon, testicles, pancreas, lung, testes, breast, uterus, ovary, and cervix.
Mutations in the STK11 gene that causes PJS are inherited in an autosomal dominant manner, meaning each first degree relative (parent, child, and sibling) of an individual with this condition has a 50% chance of inheriting the disease causing mutation. The majority of individuals with PJS inherit the condition from a parent; however, 20% of individuals have a new (de novo) mutation.
Genetics Home Reference: http://ghr.nlm.nih.gov/condition/peutz-jeghers-syndrome
American Society of Clinical Oncology: http://www.cancer.net/cancer-types/peutz-jeghers-syndrome