Critically, one-third of MDD-associated WM tract alterations identified in our main analysis (including Fmin, ILF, and SLF) demonstrated reproducible effects in the external validation cohort (|Cohen's d| > 0.31, P < 0.001, FDR q < 0.05, Fig. S12 and Table S13). The gene discussed is FOXK2; the disease is major depressive disorder.