The PreDM1 and manifest DM1 group had significantly higher NF-L relative to controls (DM1 vs. Controls Estimate = 4.43, 95% CI 3.02:5.84, P < 0.001; PreDM1 vs. Controls Estimate = 3.04, 95% CI 0.95:5.12, P < 0.01). The gene discussed is NEFL; the disease is myotonic dystrophy type 1.