Following the discovery of adenosine (A) to thymine (T) mutations in the p53 tumor suppressor gene of tumor DNA samples from BEN patients (Grollman et al., 2007), further studies of aristolochic acid were conducted which demonstrated that aristolochic acid induced these A to T mutations in human p53 sequences in vitro. These particular p53 mutation sites, which are rarely mutated in human cancers in general, are found in BEN patients (Nedelko et al., 2009). The gene discussed is TP53; the disease is neoplasm.