The predicted mean percentages of the subjects with γ-GT elevation were about 2- to 3-fold, 3- to 4-fold and 4- to 8-fold higher in the patients with the SOD2 Val/Val genotype without intellectual disability, those with the SOD2 Val/Ala or Ala/Ala genotype and intellectual disability and those with the SOD2 Val/Val genotype and intellectual disability, respectively, than in those with the SOD2 Val/Ala or Ala/Ala genotype without intellectual disability (Table 4). Here, SOD2 is linked to Intellectual disability.