The premature aging disorder Hutchinson-Gilford progeria syndrome (HGPS; OMIM #176670) results from mutations in the LMNA gene (encoding prelamin A) that block ZMPSTE24 processing, whereas the related progeroid diseases mandibuloacral dysplasia type B (MAD-B; OMIM #608612) and restrictive dermopathy (RD; OMIM #275210) result from mutations in ZMPSTE24 that diminish protease function (Barrowman et al., 2012b; Davies et al., 2009; De Sandre-Giovannoli et al., 2003; Eriksson et al., 2003; Navarro et al., 2014). Here, PPIB is linked to mandibuloacral dysplasia.