KLK3 and pachyonychia congenita: Some limitations of the present study are: in the analysis, we did not consider some confounders, that may influence the risk and the incidence of PC, such as family history of PC, screening programs for PC through prostate-specific antigen (PSA), or the fact that the IBD patients could have an increased ascertainment of PC because they are more frequently subjected to rectal examinations due to the characteristics of the disease.