In this context it is noteworthy that a large-scale investigation in BEN patients on the role of genetic polymorphisms in genes of some phase I detoxication CYP enzymes revealed a possible risk for BEN (OR 2.41) in individuals carrying CYP3A5*1 allele G6989 (Toncheva et al., 2004; Toncheva 2006). Here, CYP3A5 is linked to Balkan nephropathy.