Mutations in STK11, the gene encoding human LKB1 (hLKB1) are the cause of the Peutz–Jeghers Syndrome (PJS), a rare autosomal dominant disease, which manifests in intestinal benign polyps and mucocutaneous mispigmentations/lentigines [11,12]. The gene discussed is STK11; the disease is Peutz-Jeghers syndrome.