The following serum proteins have been investigated for PC diagnosis and prognosis using highly advanced approaches: Afamin, alpha-2-HS-glycoprotein chain B, alpha-2-macroglobulin, zinc-α2-glycoprotein (ZAG), pentraxin 3 (PTX3), spondin 2 (Spon 2), follistatine (FST), pigment epithelium-derived factor (PEDF), fibronectin 1, chromogranin A, and alpha-1-antichymotrypsin15. Here, FST is linked to pachyonychia congenita.