STK11 and Peutz-Jeghers syndrome: Peutz–Jeghers syndrome (PJS, OMIM 175200) is an autosomal dominant disorder characterized by gastrointestinal (GI) hamartomatous polyps, mucocutaneous pigmentation, and an increased risk for the development of GI and various extra-GI malignancies.[1] Germline mutations in serine/threonine kinase 11 (STK11) gene are considered to cause PJS, and more than 400 mutations in it (Human Gene Mutation Database [HGMD], http://www.hgmd.cf.ac.uk) have been identified in patients with PJS.