Inherited mutations in the genes phosphatase and tensin (PTEN), p53, STK11/LKB1, hMSH2, RB1, MEN1 and VHL give rise to predisposing syndromes, namely Cowden’s disease [45], Li-Fraumeni syndrome [46], Peutz-Jeghers syndrome [47], Lynch syndrome [48], retinoblastoma [49], Wermer syndrome [50], and von Hipple-Lindau syndrome [51], respectively. The gene discussed is STK11; the disease is Peutz-Jeghers syndrome.