GSTM1 and presbycusis: Bared et al. [16] found that people with the GST μ1 (GSTM1) null genotype cannot bind specific metabolites, and their high-frequency distortion-product otoacoustic emission amplitude is lower than that of people who express the GSTM1 gene, suggesting that the GSTM1 null genotype leads to a predisposition to presbycusis.