Twelve genes (BTG2, CCND3, CD151, CD7, CLU, CTSB, KLRK1, SPN, GSTO1, PCMT1, PRDX6, and PRF1) that were shown to be differentially expressed in PBMCs of patients with RA were also differentially expressed in PBMCs of PC patients, 8 of which (CCND3, CD151, CLU, CTSB, GSTO1, PCMT1, PRDX6, and PRF1) were in the same direction (2% commonality) [11]. The gene discussed is BTG2; the disease is pachyonychia congenita.