The investigation of manganese superoxide dismutase (Mn-SOD) polymorphism in patients with schizophrenia

There are great evidences in recent years that free oxygen radicals play an important role in the pathophysiology of schizophrenia. The present study was performed to assess whether there is genetic association between a functional polymorphism (Ala-9Val) in the human manganese superoxide dismutase (Mn- SOD) gene in schizophrenic patients (n=153) and healthy controls (n=196). The patients and controls were divided into two groups according to their gender to investigate the genomic polymorphism of Mn-SOD. Patients were also divided into two groups according to their semptoms having tardive dyskinesia (n=23) or not (n=130); three groups according to the subtypes of schizophrenia as paranoid schizophrenia (n=81), disorganized schizophrenia (n=32), and residual schizophrenia (n=35); two groups according to their antipsychotic drug doses as chlorpromazine equivalent (more and less than 300 mg/day, more and less than 400 mg/day). Significant differences in the allelic or genotypic distribution between schizophrenics and controls were observed. Ala/ Ala 14 (%9.2), Ala/Val 106 (%69.3), and Val/Val 33 (%21.6) genomic distrubition in schizophrenia was different from those of controls (46 [%23.5], 83 [%42.3], and 67 [%34.2], respectively) (pO.OOOl) (digits represent the number of patients). Decreased Ala allele was found among patients with tardive dyskinesia showing no statistically significant differences (p>0.05). These results suggest that -9Ala Mn-SOD allele may play a role in protecting the body against oxidative stress in schizophrenia and susceptibility to schizophrenia. According to our findings, it can be suggested that Ala/Val genotype can make our population more vulnerable to schizophrenia. On the other hand, -9 Ala Mn-SOD allel seems to be a important factor to be protecting of the body from oxidative stress and protecting of schizophrenic patients from tardive dyskinesia. Since Mn-SOD gene polimorphism may affect the symptomatology (clinic) of schizophrenia, the relationship between this polimorphism and tardive dyskinesia needs to be studied in a larger cohort.Key words: Manganese superoxide dismutase, gene polymorphism, schizophrenia.