Clinical and Pathological Features of CSF1R-Related Disorder Associated With the p.R777Q Pathogenic Variant

Colony-stimulating factor-1 receptor (CSF1R)-related disorder (CSF1R-RD) is a rapidly progressive neurodegenerative disease with a median onset of 43 years. More than 200 CSF1R pathogenic variants have been identified. Patients develop rapidly progressive dementia and motor symptoms, with a median disease duration of 6.8 years. The p.R777Q variant causes CSF1R-RD; it is deleterious to protein function. We describe the clinical and pathological features of CSF1R-RD associated with p.R777Q and report a new family carrying this variant. We compare the neuropathological findings of an index patient (with short-duration disease) with those of a patient with long-duration CSF1R-RD.

We present clinical and imaging data from a new family with p.R777Q. We also describe the neuropathology of an index patient and contrast these findings with features of a patient with CSF1R-RD with an 11-year disease course caused by the c.2656_2657insC variant.

We reviewed the literature on 13 individuals from 8 families with the p.R777Q variant from Asia, Europe, and North America. The mean age at onset was 41±14 years, ranging from 22 to 63 years, and the mean survival was 3.3±2.5 years. Neuropathologic studies of our index patient (10-month disease duration) revealed features consistent with CSF1R-RD. Axonal and myelin pathology was severe in the periventricular white matter. Compared with the patient with an 11-year disease duration, the index patient had less severe white matter lesions.

Compared with CSF1R-RD associated with other variants, the p.R777Q variant has an aggressive course. Compared with the patient with a long disease duration, the index patient had milder neuropathological findings. These differences may be specific to p.R777Q or associated with rapid clinical progression.