CDC73 and pachyonychia congenita: Such germline CDC73 mutations are reported to occur in 20%–40% of patients with apparently sporadic PC, and somatic CDC73 mutations have been reported to occur in ∼40%–100% of apparently sporadic PCs (Table 5 and Figure 2) (Howell et al., 2003; Shattuck et al., 2003b; Cetani et al., 2004; Guarnieri et al., 2012).