Th17/Treg imbalance is involved in periodontitis development, as indicated by enhanced Th17 response with increased IL-17A production and suppressed anti-osteoclastogenic function of Treg, which is also associated with exacerbated periodontitis during pregnancy (Hays et al., 2019; Alvarez et al., 2020). The gene discussed is IL17A; the disease is periodontitis.