SNP309 (rs2279744) is situated in promoter P2 in intron 1 of MDM2, and was shown to affect binding of transcription factor SP1, MDM2 expression, the risk, age at onset, and prognosis of human cancer, as well as p53 levels and the rate of TP53 mutation [17,18,19,20,21,22,23,24,25,26]. The gene discussed is MDM2; the disease is cancer.