Circulating miR-378a-3p as a molecular biomarker in pediatric duchenne muscular dystrophy

Abstract Early and accurate diagnosis of Duchenne muscular dystrophy (DMD) remains challenging in children with elevated creatine kinase (CK), as CK is sensitive but lacks disease specificity. Circulating microRNAs have emerged as potential biomarkers for muscle pathophysiology. We quantified circulating miR-378a-3p levels by qRT-PCR in genetically confirmed DMD patients, healthy controls, and non-DMD neuromuscular disorder patients. Non-parametric analyses with effect size estimation were employed to assess group differences. Diagnostic performance was evaluated via logistic regression and ROC curve analysis, while model stability was validated through bootstrap resampling. MiR-378a-3p was significantly elevated in DMD patients (large effect sizes) and uncorrelated with CK, age, or muscle strength within the DMD cohort. ROC analyses showed excellent discrimination for DMD vs. controls (AUC = 0.959) and good performance for DMD vs. combined non-DMD groups (AUC = 0.867). In the clinically relevant hyperCKemia subgroup, the combined miR-378a-3p and CK model showed diagnostic performance comparable to CK alone (AUC = 0.971 vs. 0.972), with slightly higher specificity at the optimal cutoff. Circulating miR-378a-3p is elevated in DMD and provides molecular information not fully captured by CK. Its potential value may lie less in routine diagnostic replacement and more in biomarker panels or longitudinal monitoring in therapeutic studies.