P2RX2 and presbycusis: Moreover, hypermethylation of CpG sites in the promoter region of SLC26A4 (DFNB4) and P2RX2 (DFNA41) genes resulted in increased risk for presbycusis in men (Xu et al., 2017), and a down-expression in elderly women with presbycusis (Bouzid et al., 2018), respectively.