Interestingly, the GSTT1 null was found to be associated with hearing damage (presbycusis) at high frequencies, which was determined by audiometry in 50 adults [39], while the presence of the GSTM1 null genotype was associated with noise-induced hearing loss as determined by pure-tone audiometry in 889 Chinese workers [40]. Here, GSTM1 is linked to presbycusis.