Blood Neurofilament Light Chain and Glial Fibrillary Acidic Protein as Candidate Biomarkers in CSF1R-Related Disorder.

Colony-stimulating factor receptor 1-related disorder (CSF1R-RD) is an underrecognized, adult-onset genetic leukodystrophy with a devastating clinical course. Disease monitoring is critical as patients with CSF1R-RD can benefit from hematopoietic stem cell transplantation. Here, we aimed to compare blood neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) levels between patients with CSF1R-RD and those with alternative diagnoses and to correlate blood biomarkers values with clinical severity. We analyzed 22 patients with CSF1R-RD and patients with fronto-temporal lobar degeneration due to GRN pathogenic variants (GRN-FTLD, n = 22), CADASIL (N = 9), cerebral adrenoleukodystrophy (13), and primary progressive multiple sclerosis (n = 14). NfL and GFAP were elevated in CSF1R-RD and GRN-FTLD as compared with the other groups. After adjusting for age, GFAP was higher in patients with CSF1R-RD compared with those with GRN-FTLD (p = 0.035). Among CSF1R-RD patients, both NfL (p = 0.0054) and GFAP (p = 0.0065) correlated with Expanded Disability Status Scale scores. For a subset of patients with cognitive testing, GFAP correlated with the processing speed index of the Wechsler adult intelligence scale (p = 0.025) and state anxiety (p = 0.0088). Our results show that blood NfL and GFAP are promising biomarkers of disease progression in patients with CSF1R-RD.