Wuolikainen et al.17 applied gas chromatography coupled to time-of-flight mass spectrometry(GC-TOF-MS) for the metabolite profiling of CSF; the authors reportedthat sporadic ALS patients had a heterogeneous metabolic signaturein the CSF, while familial ALS without superoxide dismutase-1 gene(SOD1) mutation was found to form a separate homogeneous group—glutamateand glutamine were reduced. Here, SOD1 is linked to amyotrophic lateral sclerosis.