Primary familial brain calcification (PFBC) is a neurological disease characterized by calcium phosphate deposits in the basal ganglia and other brain regions, thus far associated with SLC20A2, PDGFB, or PDGFRB mutations. We identified in multiple PFBC families mutations in XPR1, a gene encoding a retroviral receptor with phosphate export function. These mutations alter phosphate export, providing a direct evidence of an impact of XPR1 and phosphate homeostasis in PFBC.

Familial idiopathic basal ganglia calcification (IBGC) or Fahr’s disease is a rare neurodegenerative disorder characterized by calcium deposits in the basal ganglia and other brain regions, which is associated with neuropsychiatric and motor symptoms. Familial IBGC is genetically heterogeneous and typically transmitted in an autosomal dominant fashion. We performed a mutational analysis of SLC20A2, the first gene found to cause IBGC, to assess its genetic contribution to familial IBGC. We recruited 218 subjects from 29 IBGC-affected families of varied ancestry and collected medical history, neurological exam, and head CT scans to characterize each patient’s disease status. We screened our patient cohort for mutations in SLC20A2. Twelve novel (nonsense, deletions, missense, and splice site) potentially pathogenic variants, one synonymous variant, and one previously reported mutation were identified in 13 families. Variants predicted to be deleterious cosegregated with disease in five families. Three families showed nonsegregation with clinical disease of such variants, but retrospective review of clinical and neuroimaging data strongly suggested previous misclassification. Overall, mutations in SLC20A2 account for as many as 41 % of our familial IBGC cases. Our screen in a large series expands the catalog of SLC20A2 mutations identified to date and demonstrates that mutations in SLC20A2 are a major cause of familial IBGC. Non-perfect segregation patterns of predicted deleterious variants highlight the challenges of phenotypic assessment in this condition with highly variable clinical presentation.

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Aside from the direct infection of the respiratory system, cases of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)related extrapulmonary manifestations are being increasingly reported. Recently, there have been some case reports of optic neuritis following SARS-CoV-2 infection; at least, three were found to be related to myelin-oligodendrocyte glycoprotein antibody-associated disease (MOGAD). [1][2][3] | C A S E REP ORTAn otherwise healthy 60-year-old man presented with an acute onset of right-eye visual loss and pain upon eye movement for 5 days. Six weeks before symptom onset, he was diagnosed with SARS-CoV-2 pneumonia, confirmed by the detection of SARS-CoV-2 on real-time reverse transcription-polymerase chain reaction (RT-PCR) using a nasopharyngeal swab. At the time, his symptoms included fever, cough, and dyspnea for 3 days. His chest radiograph showed ground-glass opacity in both basal lungs. He was admitted to another hospital and received oral favipiravir (3600 mg/d) on day 1 and 1600 mg/d from day 2 to 5 along with prednisolone (60 mg/d).

A 45‐year‐old man developed parkinsonism 3 weeks after being diagnosed with mild COVID‐19. Levodopa and benserazide failed to improve his symptoms, necessitating ropinirole, and steroid treatment, which included a 5‐day course of methylprednisolone followed by a 3‐month oral prednisolone taper. One month after initiating steroid treatment, his symptoms improved significantly.