Indeed, several genes of innate immunity have already been associated with PC, such as the ribonuclease L (RNASEL) (Carpten et al, 2002), macrophage scavenger receptor 1 (MSR1) (Xu et al, 2002), members of the toll-like receptor (TLR) family (Zheng et al, 2004), macrophage inhibitory cytokine-1 (MIC-1) (Lindmark et al, 2004) and interleukin-1 receptor antagonist (IL1RN) (Lindmark et al, 2005). This evidence concerns the gene RNASEL and pachyonychia congenita.