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The term polyp refers to any overgrowth of tissue from the surface of mucous membranes. Intestinal polyps grow out of the lining of the small and large bowels. The polyps that arise as a result of proliferative dysplasia are termed as adenomatous polyps or adenomas. They are true neoplastic lesions and are precursors of carcinoma. The hamartomatous polyps are formed as a result of abnormal mucosal maturation. They are non-neoplastic and do not have malignant potential. There are several hereditary diseases that produce large numbers of intestinal polyps. These disorders include: familial adenomatous polyposis of the colon (MIM 175100), familial adenomatous polyposis type 2(MIM 608456), Lynch's syndrome (MIM 120435), Peutz-Jeghers syndrome (MIM 175200), Juvenile polyposis syndrome (MIM 174900) PTEN Hamartoma Tumor Syndrome (PHTS) PHTS Includes: Bannayan-Riley-Ruvalcaba Syndrome (MIM 153480), Cowden Syndrome (MIM 153480), PTEN-Related Proteus Syndrome, Proteus-Like Syndrome. Here we present spectrum of mutation detected in over six hundred Polish families with intestinal polyposis. The studies have encompassed over 30 families with Juvenile polyposis syndrome and PHTS, over 40 families with Peutz-Jeghers syndrome and almost 600 families with familial adenomatous polyposis of the colon. The study was in part financed by the Ministry of Education and Science, Poland, grant number N402 481537, N401 331936.

Genetic testing for the two major breast cancer susceptibility genes, BRCA1 and BRCA2 is widely available in North America and Europe. A few other highly-penetrant breast cancer genes have been found, including p53, BRIP1 and PALB2, but families with mutations in these are exceedingly rare. Arguably, the most relevant of the post-BRCA genes, from a clinical point of view, is CHEK2, which was first linked to breast cancer susceptibility in 2002. In Poland, there are four founder mutations of CHEK2. Three of these (IVS2+1G>A, del5395 and 1100delC) are protein-truncating mutations and one (I157T) is a missense variant. We estimated the lifetime risk of breast cancer for carriers of CHEK2 truncating mutations to be 20% for a woman with no affected relative, 28% for a woman with one second-degree-relative affected, 34% for a woman with one first-degree relative affected, and 44% for a woman with both first- and one-second degree relative affected in the Polish population. In addition we estimated that the lifetime risk for breast cancer for women who carried two different CHEK2 mutations (a truncating mutation and the missense mutation) to be 42%. Our results confirm that CHEK2 mutation screening detects a clinically meaningful risk of breast cancer, and women with a truncating mutation in CHEK2 and a positive family history of breast cancer, and women who carry two different CHEK2 mutations (the missense mutation I157T and a truncating mutation) face a lifetime risk of breast cancer above 25% and are candidates for MRI screening and for tamoxifen chemoprevention.