Gene-wide association study between the methylenetetrahydrofolate reductase gene (MTHFR) and schizophrenia in the Japanese population, with an updated meta-analysis on currently available data

Meta-analysis of MTHFR gene variants in schizophrenia, bipolar disorder and unipolar depressive disorder: Evidence for a common genetic vulnerability?

“…In line with the current results, the meta-analysis of Yoshimi et al (2010) supported an association between MTHFR C677T with schizophrenia (Yoshimi et al, 2010), similar to earlier meta-analyses (Yoshimi: random effects OR = 1.17, 95% CI: 1.07-1.29) Gilbody et al, 2007;Jonsson et al, 2008;Lewis et al, 2005;Muntjewerff et al, 2006;Shi et al, 2008;Zintzaras, 2006).…”

“…This analysis examined two SNP's associated with three psychiatric disorders, examining both combined major psychiatric disorders as well as individual diagnoses when there was evidence for diagnostic moderation. This is the first meta-analysis examining the association between MTHFR and multiple psychiatric disorders using a cross-disorder designmost meta-analyses available to date have examined the association between MTHFR C677T and diagnoses of a single psychiatric disorder Chen et al, 2009;Cohen-Woods et al, 2010;Gaysina et al, 2008;Shi et al, 2008;Yoshimi et al, 2010). Meta-analyses conducted by Lewis et al (6 articles, 2427 (Lewis et al, 2005;Muntjewerff et al, 2006).…”

Specific and common genes implicated across major mental disorders: A review of meta-analysis studies

“…For MTHFR C677T (rs1801133), seven studies supported the T allele, TT or TT/CT genotype in SZ in either mixed ethnic cohorts (Allen et al, 2008;Gilbody et al, 2006;Kim et al, 2011;Muntjewerff et al, 2006;Shi et al, 2008b;Yoshimi et al, 2010;Zintzaras, 2006), Asian (Kim et al, 2011;Shi et al, 2008b;Yoshimi et al, 2010;Zintzaras, 2006), or Caucasian samples (Shi et al, 2008b;Yoshimi et al, 2010) (Supplementary Table 1). The T allele effect in Asian and Caucasian samples in particular was however conflicted by null effects reported by two studies (Kim et al, 2011;Zintzaras, 2006) (Supplementary Table 3).…”

“…The T allele effect in Asian and Caucasian samples in particular was however conflicted by null effects reported by two studies (Kim et al, 2011;Zintzaras, 2006) (Supplementary Table 3). As sample size was not reported for some of these studies (Kim et al, 2011;Yoshimi et al, 2010), a direct comparison of significant and conflicting effects is not feasible and therefore it is not definitive whether these null effects are representative of limitations in sample size and/or composition, or whether they are due to a weak effect of this particular variant.…”

“…The role of the C allele in mixed ethnic cohorts was conflicted by null effects reported by three studies (Supplementary Table 3), one of which was in a larger cohort (Peerbooms et al, 2011) than the confirmed study (Shi et al, 2008b); the other two conflicting studies did not report total sample size (Kim et al, 2011;Yoshimi et al, 2010), so the reasons for this discrepancy is not definitive. The role of C allele was also conflicted by null effects reported by three studies in Caucasian cohorts (Supplementary Table 3); in this case, the conflicting null study used a smaller cohort (Zintzaras, 2006) than the confirmed study (Shi et al, 2008b), and the other two studies again failed to report total sample size (Kim et al, 2011;Yoshimi et al, 2010) so the reason for the discrepancy is unclear. The CC genotype effects in the mixed ethnic group (Zintzaras, 2006) was conflicted by null effects in a much larger study (Peerbooms et al, 2011), suggesting this former effect may be rather small and/or due to false positive variability.…”