Basal ganglia calcification: ‘Fahr’s disease’

Brain calcification is often detected incidentally, but basal ganglia calcification has a wide differential diagnosis, including genetic and acquired causes. Primary familial brain calcification (PFBC) (formerly 'Fahr's disease') refers to neurological disorders characterised by bilateral, symmetrical deposition of calcium-hydroxyapatite crystals in the basal ganglia and other encephalic regions, with a presumed genetic basis. Its clinical picture encompasses motor, cognitive and psychiatric manifestations in various combinations. Seven genes have been linked to PFBC since 2012, with either autosomal dominant (<i>SLC20A2</i>, <i>PDGFRB</i>, <i>PDGFB</i> and <i>XPR1</i>) or recessive (<i>MYORG</i>, <i>JAM2</i> and <i>NAA60</i>) mode of inheritance. Mendelian gene discovery has provided critical insights into the pathogenesis of PFBC. Dyshomeostasis of inorganic phosphate, impaired endothelial functions and disrupted blood-brain barrier integrity has been identified as converging pathomechanisms, which could highlight the targets of potential disease-modifying treatments. We provide a state-of-the-art overview on phenotypic features, diagnosis, aetiopathogenesis and management of PFBC.