Several genes have been proven to be the prognostic or diagnostic biomarkers of PC, such as LCN2, CLDN18, LAMC2 and SULF1(Bartsch et al., 2018; Ito et al., 2011; Kosanam et al., 2013; Lyu et al., 2018). Here, CLDN18 is linked to pachyonychia congenita.