The remaining two proteins with elevated levels in OF of PC patients and included in our biomarker combination were Lactoperoxidase and Peptidyl-prolyl cis–trans isomerase B. The latter is also called Cyclophilin B (CypB) and is a 21-kDa protein belonging to the cyclophilin family of peptidyl-prolyl cis–trans isomerase. This evidence concerns the gene PPIB and pachyonychia congenita.