C9orf72 and amyotrophic lateral sclerosis: It also identified an asymptomatic carrier of a pathogenic C9orf72 variant, and strongly correlated with ALS disease progression measures (Pearson's R = 0.66, p = 3.71 × 10−9).<h4>Conclusions</h4>We identified DNA methylation signals from multiple tissue types in ALS cfDNA, highlighting diverse tissue involvement in ALS pathology.