NFL and GFAP in (pre)symptomatic RVCL-S carriers: a monogenic cerebral small vessel disease

Abstract

BackgroundNeurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) have emerged as biomarkers for cerebral small vessel disease (SVD). We investigated their role in a hereditary SVD model, retinal vasculopathy with cerebral leukoencephalopathy and systemic manifestations (RVCL-S).MethodsNfL and GFAP levels of 17 pre-symptomatic, 22 symptomatic RVCL-S mutation carriers and 69 controls were measured using a Simoa assay. We assessed the association of serum and cerebrospinal fluid (CSF) levels of NfL and GFAP with RVCL-S symptomatology and neuropsychological functioning.ResultsSerum and CSF NfL levels were higher in symptomatic RVCL-S compared to controls ≥ 45 years (33.5 pg/mL vs. 9.2 pg/mL, p < 0.01; 8.5*102 pg/mL vs. 3.9*102 pg/mL, p < 0.01, respectively). Serum NfL levels were higher in symptomatic RVCL-S than pre-symptomatic carriers (33.5 pg/mL vs. 5.9 pg/mL, p = 0.02). Pre-symptomatic RVCL-S carriers had increased CSF NfL levels compared to controls < 45 years (5.2*102 pg/mL vs. 1.9*102 pg/mL, p < 0.01). No differences were found in GFAP levels across groups, but in RVCL-S carriers higher serum levels of both NfL and GFAP were linked to poorer global cognitive functioning (β[95%CI] = − 2.86 [− 5.58 to − 0.13], p = 0.04 and β[95%CI] = − 6.85 [− 11.54 to − 2.15], p = 0.01, respectively) and prolonged psychomotor test times (β[95%CI] = 6.71 [0.78–12.65], p = 0.03 and β[95%CI] = 13.84 [3.09–24.60], p = 0.01).DiscussionHigher levels of serum NfL and GFAP are associated with worse cognitive functioning in RVCL-S carriers and may serve as marker for disease progression. CSF NfL levels may serve as early marker as pre-symptomatic RVCL-S patients already show differences compared to young controls.