IRF9 and pachyonychia congenita: Moreover, the genetic alterations analysis revealed that IRF1, IRF2, IRF3, IRF4, IRF5, IRF6, IRF7, IRF8 and IRF9 were altered in 6, 8, 8, 2.7, 6, 6, 4, 4, and 4% of the queried PC samples, respectively (Fig. 5B).