PIK3CA and pachyonychia congenita: For instance, TP53, SPOP, PIK3CA, BRCA2 and AR genes alterations have been demonstrated in PC in various populations (Bookstein et al., 1993; Carroll et al., 1993; Taplin et al., 1995; Li et al., 1997; Edwards et al., 2003c; Thomas et al., 2007; Taylor et al., 2010; Barbieri et al., 2012; Beltran et al., 2013).