STK11 and Peutz-Jeghers syndrome: Germline mutations in serine/threonine kinase 11 (STK11, OMIM 602216) gene which impairs its kinase activity are considered to cause PJS, and more than 400 of them identified in patients with PJS have been recorded in Human Gene Mutation Database (HGMD, http://www.hgmd.cf.ac.uk).