Visualizing Molecular Alterations and Peripheral Detections in Asymptomatic Amyotrophic Lateral Sclerosis Using b-isox-based Detection

Abstract Proteinopathies cause severe diseases, particularly neurodegenerative ones. Early detection is crucial for effective therapy but is especially challenging in sporadic cases. In this study, we demonstrate that proteinopathy-associated proteins can be accurately isolated from plasma using b-isox in onset-stage ALS, even in sporadic cases. Specific b-isox precipitates were found in 98.5% of ALS patients but were absent in healthy controls, correlating negatively with ALS Functional Rating Scale-Revised (ALSFRS-R) scores. Proteomic analysis of these precipitates revealed that sporadic cases had fewer proteins, but with greater changes in their levels compared to familial cases and the newly identified biomarker CA1 forms fibers in vitro and parallels TDP-43 progression, highlighting its significance in TDP-43 proteinopathies. Significantly, the b-isox-based ELISA effectively detects early-stage ALS with an AUC of 0.96 (95% confidence interval 0.922–1.00) for C9orf72 poly(GR) amyloid oligomers, even in asymptomatic stages of non-C9orf72 inherited patients, potentially revolutionizing proteinopathy treatment and understanding.