In this study, we present a case of CSF1R-microglial encephalopathy in a patient with a splice mutation (c.2654 + 1G>A) in the CSF1R gene, a family history of early-onset dementia, and a CSF biomarker profile suggesting Alzheimer’s disease-related changes. This evidence concerns the gene CSF1R and early-onset autosomal dominant Alzheimer disease.