Objective: To explore the association between serum concentrations of folic acid and homocysteine (HCY), 5, 10-methylenetetrahydrofolate reductase (MTHFR) C667T polymorphism and schizophrenia.
Methods: A total of 130 schizophrenics (schizophrenia group) from our hospital and 80 healthy individuals (control group) were enrolled. The serum concentration of homocysteine was measured by the electrochemical luminescence method, the concentration of serum folic acid by enzymatic cycling assay and MTHFR C667T genotype by PCR-DNA microarray. And positive and negative syndrome scale (PANSS) was used to evaluate the mental symptoms.
Results: (1) Serum HCY level in schizophrenia group was higher than that in control group [(20 ± 10) vs (11 ± 3) µmol/L; P < 0.001] while serum folate level in schizophrenia group was lower than that in control group [(6 ± 4) vs (9 ± 3) ng/ml; P < 0.001]; (2) the frequencies of CC, CT and TT in MTHFR C677T alleles were 13.1%, 50.0% and 36.9% in schizophrenia group versus 30.0%, 47.5% and 22.5% in control group respectively. Statistical significant inter-group difference existed in the frequencies of genotypes (χ² = 36.806, P < 0.05) . The frequencies of T and C alleles were 61.9%, 38.1% in schizophrenia group versus 46.25%, 53.75% in control group respectively. Statistical significant inter-group difference existed in the frequency of T allele (χ² = 9.872, P < 0.05). The frequency of TT genotype in schizophrenia group was 61.9% versus 22.5% in control group. Statistically significant inter-group difference existed in the frequency of TT homozygous mutation (χ² = 4.780, P < 0.05); (3) correlation analysis showed that serum folate level in schizophrenia group had a negative correlation with HCY level (r = -0.418, P < 0.001) . Serum HCY level had a positive correlation with negative symptoms scores (r = 0.345, P < 0.001) and serum folate level was negatively correlated with negative symptoms scores (r = -0.386, P < 0.001); (4) the serum HCY level in schizophrenia group with TT genotype was significantly higher than those with CC and CT genotypes (P < 0.05).
Conclusion: There is a certain correlation between the serum levels of folate and HCY and the symptoms of schizophrenia. And MTHFR C677T polymorphism is a possible risk factor for schizophrenia.