Also, the limitation is the lack of BEN patients or controls carrying all six non-risk associated genotypes (KEAP1*CC, Nrf2*CC, GSTPAB*AA, GSTPCD*CC, GPX3*TT, MDR1*CC) and all six risk-associated genotypes (KEAP1*GG, Nrf2*AA, GSTPAB*GG, GSTPCD*TT, GPX3*CC, MDR1*TT). The gene discussed is GPX3; the disease is Balkan nephropathy.