Eick et al. compared the levels of LL-37 in GCF, saliva, and neutrophil-derived enzymes, which revealed the fact that dysfunctional cathepsin C in patients of Papillon-Lefevre syndrome caused the deficit in immunomodulatory and antimicrobial functions of LL-37 in GCF, leading to severe periodontal disease. This evidence concerns the gene CTSC and periodontal disorder.