Clinical and radiological diversity in genetically confirmed primary familial brain calcification

Primary familial brain calcification (PFBC) is a rare neuropsychiatric disorder with characteristic symmetrical brain calcifications. Patients with PFBC may have a variety of symptoms, although they also may be clinically asymptomatic. Parkinsonism is one of the most common movement disorders; however, the underlying mechanism remains unclear. This condition is typically transmitted in an autosomal dominant fashion. To date, mutations in SLC20A2, PDGFRB, PDGFB, and XPR1 have been reported to cause PFBC. The aim of the study was to identify the genetic cause of brain calcification in probands from three PFBC families and in 8 sporadic patients and to perform clinical and radiological assessments focusing on parkinsonism in mutation carriers. Three familial PFBC probands and their relatives and eight sporadic patients affected with brain calcifications were enrolled in this study. Whole-exome sequencing identified three novel mutations: c.269G > T, p.(Gly90Val) and c.516+1G > A in SLC20A2 in familial cases, and c.602-1G > T in PDGFB in a sporadic patient. The c.516+1G > A mutation resulted in exon 4 skipping in SLC20A2 (p.Val144Glyfs*85). Dopamine transporter single photon emission computed tomography using (123)I-ioflupane and (123)I-metaiodobenzylguanidine cardiac scintigraphy revealed pre-synaptic dopaminergic deficit and cardiac sympathetic nerve dysfunction in two SLC20A2-related PFBC patients with parkinsonism.