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 (SLC20A2, PDGFRB, PDGFB and XPR1) or recessive (MYORG, JAM2 and NAA60) 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.