In humans, hemizygous germline mutations in PTEN or LKB1 lead to Cowden’s and Peutz–Jegher’s syndromes, respectively, which are characterized by the appearance of multiple benign tumors, commonly arising in the GI tract, skin, and mucous membranes, with an age of onset typically between 10 and 30 years old [114,115]. The gene discussed is PTEN; the disease is benign neoplasm.