miRNA Biomarkers Diagnose Amyotrophic Lateral Sclerosis in Circulating Blood.

A rapid, accurate diagnostic test for amyotrophic lateral sclerosis (ALS) would reduce diagnostic delays and improve patient outcomes. We extracted eight circulating miRNAs from 788 blood plasma samples and analyzed them using qPCR for ALS diagnostic accuracy. The biomarker parameters were established previously using 449 individual blood samples and applied prospectively to an independent cohort for validation of a predictive model. The primary outcome was ALS classification accuracy as measured by diagnostic sensitivity, specificity, positive and negative predictive values (PPV, NPV), and area under the curve (AUC). The secondary outcome was comparative fold-regulation values determined prior to data collection. The diagnostic test had an AUC of 0.98 (95% CI 0.97-0.99), with 97% sensitivity (95% CI 96-98), 93% specificity (95% CI 90-96), 93% PPV (95% CI 91-96), and 97% NPV (95% CI 96-98). The fold-regulation values exceeded or were equal to prior calculated values. Streamlined methods resulted in higher diagnostic accuracy, cut both assay time and cost, reduced technical barriers, and enhances the feasibility for widespread clinical adoption. The high accuracy of this diagnostic biomarker suggests that continued evaluation is warranted.