OTA is less likely than aristolochic acid to induce A to T transversions in the p53 gene of BEN patients as it is a weak mutagen at best (Nedelko et al., 2009), and the results of another study have shown that hypoxanthine-guanine phosphoribosyl transferase (HPRT) gene base substitutions of mammalian cells exposed to OTA did not include A to T transversions, and were similar to the spontaneous mutation pattern (Palma et al., 2007). Here, HPRT1 is linked to Balkan nephropathy.