Background and Aims:
J.L.Roffman et al. reported (2011) that folate metabolism disturbances (T-allele carriage of genetic polymorphism of folate metabolism key enzyme MTHFR677C>T) are associated with severity of negative symptoms of schizophrenia. In those study patients received antipsychotics, so it is impossible to exclude the secondary pharmacogenic nature of negative symptoms. The purpose of this study was to evaluate the association of T-allele of MTHFR677C>T with the severity of negative symptoms of schizophrenia at different stages of treatment to exclude the pharmacogenic nature of the negative symptoms associated with folate deficiency.
Methods:
Patients with schizophrenia were examined with PANSS during the treatment in hospital (more than 10 days, n=106), and in the first 1-3 days from the admission to hospital (n=59) when the impact of antipsychotic treatment was minimal and examined by the PCR method for the carriage of alleles of polymorphism MTHFR677C>T. Both groups of patients were comparable by gender, age, distribution of alleles of MTHFR677C>T. 
Results:
Carriers of the T-allele vs patients with wild genotype after 10 days of treatment had the greater severity of some negative symptoms: affect flattening (p=0.029), passive-apathic social seclusion (p=0.014) , stereotyped thinking (p=0.044), which is consistent with the results of J.L.Roffman. However, patients who were examined at the begining of hospitalization had no differences in the severity of negative symptoms between subgroups with/without T-allele. 
Conclusions:
More pronounced negative symptoms in patients with T-allele  in comparison with patients with "wild" CC genotype examined during  inpatient treatment may be antipsychotic-induced secondary negative symptoms, but not primary symptoms of schizophrenia.

17 - SECONDARY BUT NOT PRIMARY NEGATIVE SYMPTOMS OF SCHIZOPHRENIA ARE ASSOCIATED WITH CARRIAGE OF MINOR ALLELE OF GENETIC POLYMORPHISM MTHFR677C AND GT;T