SOD1 and amyotrophic lateral sclerosis: Voxel-based comparative analyses between C9orf72-ALS and C9orf72-matchedsALS patients, and between SOD1-ALS and SOD1-matchedsALS patients, revealed two significant clusters of relative hypometabolism and one cluster of relative hypermetabolism in C9orf72-ALS patients in relation to C9orf72-matchedsALS patients.