"Lynch syndrome is an autosomal dominant condition. This means that a person who carries one copy of a mutation in any of the 5 genes known to cause Lynch syndrome is at increased risk to develop multiple adult-onset cancers, especially those of the colon, uterus and ovaries.
A person who carries two mutations in the same gene of any of the genes associated with Lynch syndrome (MLH1, MSH2, MSH6, PMS2) has a completely different syndrome called Constitutional Mismatch Repair Deficiency (CMMRD). This usually occurs when that person inherits one mutation from the father and the other from the mother. This rare condition is associated with a high risk of early-onset cancers, including childhood onset cancers of the brain and blood. Café-au-lait spots (flat, light brown birthmark-like marks on the skin), are also common."
LI FRAUMENI SYNDROME- LFS - TP53
"Cowden syndrome (PTEN) is a rare hereditary cancer syndrome. The incidence is 1 in 200.000. The estimated cumulative lifetime risk for breast cancer is 67–85 % and patients may develop cancers of thyroid, endometrial, colorectal, renal and melanoma. Hamartomatous lesions are characteristic manifestations of this syndrome."