NAT2 and presbycusis: Independent studies have showed a significant association between NAT2 polymorphisms and presbycusis, namely NAT2∗6A in the Turkish population (Ünal et al., 2005b) and in the European population (Van Eyken et al., 2007) with Caucasian subjects carrying a NAT∗6A mutant allele having an increased risk to Presbycusis (Bared et al., 2010).