No association between Ala9Val functional polymorphism of MnSOD gene and schizophrenia in a representative Italian sample

Reactive oxygen species (ROS) have been suggested to play an important role in physiopathology of schizophrenia. The polymorphisms in the genes encoding antioxidant enzymes, such as manganese superoxide dismutase (MnSOD) should, thus, result in predisposition to this psychiatric disorder. A functional amino acid polymorphism (Ala9Val) has been described in the signal sequence of enzyme associated with a decreased defense capacity against oxidative stress. Preliminary evidence in a Turkey population indicated that this polymorphism contributes to physiopathogenesis of schizophrenia. The object of this study was to verify the association between Ala9Val and schizophrenia in a representative Italian sample. The polymorphism was genotyped by PCR amplification and Single-Stranded Conformational Polymorphism (SSCP) analysis in 212 DSMIV schizophrenic patients and 257 healthy volunteers. No association was observed between cases and controls (genotype and allele frequencies: p = 0.72, p = 0.55, respectively) even when a sample stratification for gender, age at onset and diagnostic subtypes was performed. This suggests that the gene variant could not be a risk factor for schizophrenia susceptibility in an Italian sample.