HSPG2 and pachyonychia congenita: Datta et al. (Datta et al., 2006) demonstrated that perlecan/HSPG2, a candidate gene for the CAPB locus with familial risk of brain and PC, is a component of Sonic Hedgehog (SHH) signaling, and its expression in PC tissues correlates with a high Gleason score and rapid cell proliferation.