SPECT 123I-ioflupane imaging in four CSF1R mutation carriers found preserved presynaptic dopamine transporter binding in three patients with parkinsonism, indicating motor deficits may arise from white-matter/ connectivity disruption rather than primary nigrostriatal degeneration.

Although sample size is small, the finding links CSF1R-related microgliopathy to non-dopaminergic mechanisms of parkinsonism, pointing toward microglial/white-matter–targeted therapeutic strategies rather than classic dopaminergic approaches for this subtype.

AIM OF THE STUDY: CSF1R-related disorder (CSF1R-RD) is a rare, autosomal dominant microgliopathy characterized by leukoencephalopathy. While extrapyramidal symptoms are common, the underlying integrity of the presynaptic dopaminergic system in these patients remains poorly understood. The aim of our study was to analyze dopamine transporter availability using single-photon emission computed tomography (SPECT) 123I-ioflupane in patients with CSF1R mutations to differentiate the pathophysiology of their parkinsonism. MATERIAL AND METHODS: We conducted a retrospective review of 112 electronic medical charts from a large tertiary referral medical center. Four patients (3.6%) with CSF1R variants underwent SPECT 123I-ioflupane imaging. Clinical data, MRI findings, and genetic pathogenicity were assessed. RESULTS: SPECT 123I-ioflupane results were normal i n 3 patients, despite t he presence of parkinsonian symptoms, i ncluding tremor, rigidity, and bradykinesia. The only patient with an abnormal SPECT 123I-ioflupane result was a 70-year-old with a pathogenic CSF1R c.1924C > T, p.Gln642* variant and a clinical phenotype of classic Parkinson disease. CONCLUSIONS AND CLINICAL IMPLICATIONS: Parkinsonism in CSF1R-RD may present with a normal SPECT 123I-ioflupane results, suggesting that motor deficits arise from white matter degradation and disrupted connectivity rather than primary nigrostriatal loss.