Serum neurofilament light chain but not serum glial fibrillary acidic protein is a marker of early Huntington’s disease

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BackgroundHuntington’s disease (HD) is caused by CAG trinucleotide expansion on chromosome 4, leading to mutant Huntingtin production. Premanifest carriers show no obvious clinical signs, and early symptoms progress slowly. Fluid biomarkers like neurofilament light (NfL) and glial fibrillary acidic protein (GFAP), measurable in cerebrospinal fluid and serum (sNfL, sGFAP), offer potential predicting HD progression.ObjectiveTo assess the role of sGFAP and sNfL and clinical biomarkers in different disease stages and correlate with disease progression.MethodsHD mutation carriers were categorized into clinical stages according to their motor symptoms and functional capacities. The Unified HD Rating Scale, cognitive assessments and olfactory tests were used to characterize the patients clinically. Furthermore, sNfL and sGFAP levels were assessed.ResultsWe consecutively included 44 HD mutation carriers (13 premanifest HD (preHD), 18 in early (early HD) and 13 in advanced (advanced HD) disease stages) and 19 healthy controls (HC). Advanced HD patients performed worse on all clinical tasks and had higher sGFAP and sNfL levels compared to other groups (all p values < 0.05). We did not find difference in sGFAP levels between the preHD, early HD and HC group (all p values > 0.05). In contrast, sNfL levels differed significantly between preHD and early HD, and HC (all p values < 0.05). ROC curve analysis revealed that the AUC of sGFAP (0.970) exhibited superior discriminatory accuracy compared to sNfL (0.791) levels in separating advanced from early HD patients. By contrast, ROC curve analysis revealed that the AUC of sNFL (0.988) exhibited superior discriminatory accuracy compared to sGFAP (0.609) levels in separating all HD mutation carriers from HC.ConclusionsOur study indicates that sNfL can detect changes in very early and premanifest HD stages, whereas sGFAP showed differences in more advanced stages only.