Because Bach2 is known to act as a proapoptotic factor by repressing the antiapoptotic factor HO-1 expression [25], and because the increased HO-1 and miR-193a-5p and the decreased Bach2 were found in PC tissues, we sought to investigate the relationship between HO-1, miR-193a-5p and Bach2. The gene discussed is HMOX1; the disease is pachyonychia congenita.