For the schizophrenia patients, the correlation analysis with serum IGF-2 levels revealed a significant association between IGF-2 levels and the PANSS negative scores (r = -0.452, p = 0.009), but no significant associations between serum IGF-2 levels and PANSS total scores, positive scores or general scores (all p > 0.05) (Table 4). Here, IGF2 is linked to schizophrenia.