ABCB1 and Balkan nephropathy: Furthermore, the two other investigated polymorphisms of GPX3 and MDR1 did not significantly influence the risk for BEN development, although a slight increase in odds ratio was noted, namely, regarding GPX3 polymorphism, we observed that carriers of at least one copy of variant GPX3*C allele (GPX3*TC*CC genotype) were at moderately increased susceptibility towards BEN development.