SOD1 and amyotrophic lateral sclerosis: We observed that both SOD1 (2.98 ± 1.60%) and sporadic ALS patients (4.22 ± 1.56%) had lower D-loop methylation levels compared to both control subjects (5.25 ± 1.57%; p = 0.0001, 95% CI 0.94 to 3.57 and p = 0.02, 95% CI 0.09 to 1.95, respectively) and C9orf72 ALS patients (5.91 ± 1.58%; p < 0.0001, 95% CI − 4.58 to − 1.27 and p = 0.01, 95% CI 0.28 to 3.10, respectively).