KRAS and pachyonychia congenita: Of these mutations, Kras is found to be mutated in almost all cases (75–90%) of PC and represents an early event in the development and progression of this malignancy (Almoguera et al, 1988; Shibata et al, 1990; Caldas and Kern, 1995; Dergham et al, 1997; Moskaluk et al, 1997; Wang et al, 2002).