Among them, CASP9, MTOR, AKT1, TERT, MYC, and NANOG are highly expressed in the normal group, while BRCA1, HSP90 AA1, MET, TNF, CASP8, STAT1, MYD88, CASP3, TLR4, IL1 A, PTGS2, HIF1 A, AREG, MMP9, TGFB1, HMOX1, IL6, NFE2L2, STAT3, NFKB1, PDGFRB, CTNNB1, MMP2, VIM, AXL, PTK2, TJP1, MAPK3, and PPARG are highly expressed in the PC group. The gene discussed is MMP9; the disease is pachyonychia congenita.