The CSF IFN-γ levels were markedly increased in the bulbar (301.29±22.84 pg/ml) and limb (366.32±18.55 pg/ml) onset subgroups compared with the non-ALS patients (172.22±17.58 pg/ml, P<0.01), but no difference was detected between the bulbar and limb onset subgroups (P>0.05). This evidence concerns the gene IFNG and amyotrophic lateral sclerosis.