CTSC and Papillon-Lefèvre syndrome: However, the absence of active HNE in PMN is tolerated, as seen in people with the congenital cathepsin C deficiencies Haim-Munck and Papillon-Lefèvre syndrome, in the clinical use of the HNE inhibitors alvelestat and sivelestat [20,21], and in clinical trials of novel cathepsin C inhibitors [44,45,46].