A family with hereditary diffuse leukoencephalopathy with spheroids caused by a novel c.2442 + 2T > C mutation in the CSF1R gene

Clinical phenotypes of hereditary diffuse leukoencephalopathy with spheroids (HDLS), a familial progressive neurodegenerative disorder affecting the white matter of the brain, are heterogenous and may include behavioral and personality changes, memory impairment, parkinsonism, seizure, and spasticity. Thus, HDLS is frequently unrecognized and misdiagnosed. Heterozygous mutations located within the kinase domain of the gene encoding the colony-stimulating factor 1 receptor (CSF1R), a cell surface receptor with key roles in development and innate immunity, have been shown in HDLS. These different gene mutations may be related to the various clinical phenotypes. We report here a newly identified family with HDLS harboring a mutation in the CSF1R gene. We examined clinical and neuropathological features in three members of this family. These patients presented with affective incontinence, memory impairment, and executive dysfunction at onset, and revealed nonfluent aphasia, parkinsonism, and seizure as the disease progressed. We identified a novel CSF1R splice site mutation (c.2442 + 2T > C) in intron 18 for two of the patients. MRI of these patients revealed progressive, frontotemporal-predominant, confluent leukoencephalopathy. We also observed severe myelin loss, axonal degeneration, and abundant axonal spheroids, astrocytes, and microglia in the cerebral white matter, consistent with HDLS neuropathological features. Additionally, we identified atypical neuropathological findings for HDLS, including neuronal loss and gliosis with ballooned neurons and central chromatolysis in the frontal cortex and hippocampus. This report provides further evidence for the clinical and neuropathological heterogeneity of HDLS.