SOD1 and amyotrophic lateral sclerosis: Plasma neurofilaments are also associated with reduced lifespan, more aggressive pathological phenotypes, and the presence of C9orf52 expansion [103,104]; their levels are elevated up to five years before disease onset in sporadic and familial ALS [105,106], and their presence indicates phenoconversion in clinically asymptomatic mutant SOD1 carriers [105].