- July 28, 2026
Product:
GFAP AQ Singleplex
Topic:
Neurology
Disease Area:
Healthy Aging
Sample Type:
Dried Plasma Spot (DPS)
Abstract
Objective
To evaluate the diagnostic accuracy of glial fibrillary acidic protein (GFAP) measured in dried plasma spots versus conventional plasma- and serum-GFAP testing for assessment of disease severity in aquaporin-4 immunoglobulin G–positive neuromyelitis optica spectrum disorder (AQP4-IgG+ NMOSD).
Methods
A neuroimmunological prospective cohort of remission samples from 70 participants with the diagnoses AQP4-IgG+ NMOSD (n = 19), myelin oligodendrocyte glycoprotein antibody–associated disease (MOGAD; n = 9), relapsing–remitting multiple sclerosis (RRMS; n = 28) and healthy controls (HC; n = 14) from a single center were included. GFAP concentrations were measured in frozen and thawed plasma and paired dried plasma spot (DPS) samples using an ultrasensitive proximity ligation–based assay (nucleic acid–linked immuno-sandwich assay; NULISA). In NMOSD, GFAP was additionally quantified in paired serum samples using a single-molecule array (Simoa) assay as a reference. Cross-matrix correlations, diagnostic performance, and associations with neurological disability were evaluated.
Results
GFAP concentrations measured by NULISA correlated strongly between plasma and DPS samples across diagnostic groups and healthy controls. In NMOSD, plasma GFAP measured by NULISA showed strong concordance with serum GFAP quantified by Simoa. DPS-derived and plasma-derived GFAP demonstrated good diagnostic accuracy for AQP4-IgG+ NMOSD and was significantly associated with neurological disability as measured by the Expanded Disability Status Scale (EDSS). Group-wise comparisons across plasma and DPS showed retained elevation of GFAP in AQP4-IgG+ NMOSD compared with the other diagnostic groups and healthy controls.
Interpretation
GFAP quantification using the NULISA platform is feasible in plasma and DPS samples and enables reliable biomarker assessment in a potentially remote-compatible setting. DPS-derived GFAP measurements retained meaningful information on disability in NMOSD and may provide an analytical framework for future studies evaluating minimally invasive capillary or self-sampling approaches.
Authors and Affiliations
Felix Wohlrab¹, Evelyn Alvarez², Roua Hamdi¹, Bingqing Zhang², Hayeun Ji², Niyati Jhaveri², Patrick Schindler³˒⁴, Pedro Sanchez³, Pia S. Sperber³˒⁴, Tanja Schmitz-Hübsch³, Frederike C. Oertel¹˒⁴˒⁵, Nisa Vorasoot⁶, Najib Kissani⁷, Falko Böhringer⁸, Jens Kuhle⁹˒¹⁰, Anne-Katrin Pröbstel⁹˒¹¹˒¹², Xiao-Jun Ma², Péter Körtvelyessy⁴˒⁸˒¹³, Patrick Waters¹⁴, and Friedemann Paul¹˒³
¹ Experimental and Clinical Research Center (ECRC), Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
² Alamar Biosciences, Fremont, California, USA
³ Neuroscience Clinical Research Center (NCRC), Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
⁴ Department of Neurology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
⁵ Einstein Center Digital Future Berlin, Berlin, Germany
⁶ Division of Neurology, Department of Medicine, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
⁷ Laboratory of Clinical and Experimental Neuroscience, Faculty of Medicine, Cadi Ayyad University, Marrakech, Morocco
⁸ Labor Berlin – Charité Vivantes Services GmbH, Berlin, Germany
⁹ Multiple Sclerosis Center and Research Centers for Clinical Neuroimmunology and Neuroscience (RC2NB) Neurology, University and University Hospital Basel, Basel, Switzerland
¹⁰ Department of Biomedicine and Clinical Research, University Hospital and University of Basel, Basel, Switzerland
¹¹ Center for Neurology, Department of Neuroimmunology and Neuromuscular Diseases, University Hospital and University Bonn, Bonn, Germany
¹² German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
¹³ German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
¹⁴ Oxford Autoimmune Neurology Diagnostic Laboratory, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK