XPR1 and bilateral striopallidodentate calcinosis: Aiming to identify novel pathogenic variants underlying PFBC, we first screened a cohort at UCL, comprising 78 cases from 53 families with PFBC who were negative for pathogenic variants in genes already linked to PFBC (SLC20A2, PDGFB, PDGFRβ, XPR1, MYORG, JAM2).