CDC73 and pachyonychia congenita: In the absence of a family history, the diagnosis of sporadic PC should be considered, and germline mutational analysis of CDC73 undertaken as >30% of such patients will have a germline CDC73 mutation, and will therefore be at high risk of developing HPT‐JT‐associated tumors (Figure 1) (Thakker et al., 2012; Eastell et al., 2014; Wells et al., 2015; Thakker, 2016).