Tumor necrosis factor haplotype analysis amongst schizophrenia probands from four distinct populations in the Asia-Pacific region

Haplotypes of TNFα/β Genes Associated with Sex-Specific Paranoid Schizophrenic Risk in Tunisian Population

Several medical research findings have announced a strong association between the biology of cytokines and various brain activities. Since growing evidences suggest the crucial and complex role of the tumor necrosis factor in the CNS, we have hypothesized that functional genetic variants of the LTA and TNFA genes (LTA +252A/G (rs909253) and TNFA -857C/T (rs1799724) and TNFA -238G/A (rs361525)) may be involved in the predisposition to schizophrenia. This research is based on a case-control study. The RFLP-PCR genotyping was conducted on a Tunisian population composed of 208 patients and 208 controls. We found a strong significant overrepresentation of the minor alleles (G, T, and A, respectively) in all patients compared with controls (p = 0.003, OR = 1.55; p = 0.005, OR = 1.78; and p = 0.0001, OR = 1.74, respectively). This correlation was confirmed for male but not for female patients. Interestingly, the frequencies of the minor alleles were significantly more common among patients with paranoid schizophrenia when compared with controls (p = 0.003, OR = 1.75; p = 5 · 10^-6, OR = 3.04; and p = 4 · 10^-6, OR = 2.35, respectively). This potential association was confirmed by a logistic binary regression analysis only for the development of the paranoid form of schizophrenia (p = 0.001/OR = 2.6; p = 0.0002/OR = 3.2; and p = 0.0004/OR = 3.1, respectively) and remained not significant for the other subtypes. Moreover, our study showed an important association between GCA haplotype and the development of this pathological form (p = 10^-4, OR = 3.71). In conclusion, our results proved a significant association between the three polymorphisms and paranoid schizophrenia, at least in the Tunisian population, suggesting a substantially increased risk for paranoid schizophrenia with dominant inheritance of these three minor alleles.

Tumor necrosis factor-alpha -1031T/C polymorphism is associated with cognitive deficits in chronic schizophrenia patients versus healthy controls

Recent compelling research has demonstrated a pathophysiologic role for proinflammatory cytokines of microglial origin in decreasing neurocognitive function. Psychiatric diseases are already known to have reduced cognitive function and are also associated with increased inflammation. To elaborate on these data, our study aims to investigate how a particular polymorphism of the tumor necrosis factor gene, TNF-α -1031T/C, affects neurocognitive performance in patients with schizophrenia. We recruited 905 patients with schizophrenia and 571 healthy control subjects. We employed the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) to test for neurocognitive function and the positive and negative syndrome scale to evaluate schizophrenia severity. The -1031T/C polymorphism was genotyped in both healthy controls and schizophrenic patients. Our results demonstrate that patients with the C allele (either T/C or C/C) possessed increased immediate memory index, visuospatial/constructional index, and RBANS total scores as compared to patients without it (p < .05). In healthy controls, there was no significant difference across genotypes (p > .05). Our findings demonstrate that the TNF-α -1031T/C polymorphism may not play a role in the susceptibility of schizophrenia itself, but may be involved in the cognitive deficits of schizophrenia. This suggests an important role for cytokine signaling in mediating the severity of cognitive dysfunction in schizophrenia.

Tumor necrosis factor-α and -β genetic polymorphisms as a risk factor in Saudi patients with schizophrenia

BACKGROUND

Schizophrenia is one of the most common devastating psychiatric disorders that negatively affects the quality of life and psychosocial functions. Its etiology involves the interplay of complex polygenic influences and environmental risk factors. Inflammatory markers are well-known etiological factors for psychiatric disorders, including schizophrenia.

OBJECTIVE

The aim of this study was to investigate the association of proinflammatory cytokine genes, tumor necrosis factor (TNF)-α (-308G/A) and TNF-β (+252A/G) polymorphisms with schizophrenia susceptibility.

SUBJECTS AND METHODS

TNF-α and TNF-β genes were amplified using amplification refractory mutation system primers in 180 schizophrenia patients and 200 healthy matched controls recruited from the Psychiatry Clinic of Prince Sultan Military Medical City, Riyadh. The frequencies of alleles and genotypes of TNF-α (-308G/A) and TNF-β (+252A/G) polymorphisms in patients were compared with those in controls.

RESULTS

The frequencies of TNF-α (-308) allele A and genotype GA were significantly higher, while those of allele G and genotype GG were lower in schizophrenia patients as compared to controls, indicating that genotype GA and allele A of TNF-α (-308G/A) may increase susceptibility to schizophrenia, while genotype GG and allele G may reduce it. On the other hand, the distribution of alleles and genotypes of TNF-β (+252A/G) polymorphism does not differ significantly in patients from controls; however, the frequency of genotype GG of TNF-β (+252A/G) was significantly higher in male patients than in female patients. The distribution of TNF-α (-308G/A) and TNF-β (+252A/G) polymorphisms was almost similar in schizophrenia patients with negative or positive symptoms.

CONCLUSION

TNF-α (-308G/A) and TNF-β (+252G/A) polymorphisms may increase the susceptibility to schizophrenia in Saudi patients and could be a potential risk factor for its etiopathogenesis. However, further studies are warranted involving a larger sample size to strengthen our findings.

Genetics of schizophrenia from a clinicial perspective

Schizophrenia (SZ) is a common disorder that runs in families. It has a relatively high heritability, i.e., inherited factors account for the major proportion of its etiology. The high heritability has motivated gene mapping studies that have improved in sophistication through the past two decades. Belying earlier expectations, it is now becoming increasingly clear that the cause of SZ does not reside in a single mutation, or even in a single gene. Rather, there are multiple DNA variants, not all of which have been identified. Additional risk may be conferred by interactions between individual DNA variants, as well as 'gene-environment' interactions. We review studies that have accounted for a fraction of the heritability. Their relevance to the practising clinician is discussed. We propose that continuing research in DNA variation, in conjunction with rapid ongoing advances in allied fields, will yield dividends from the perspective of diagnosis, treatment prediction through pharmacogenetics, and rational treatment through discoveries in pathogenesis.

Cytokines in schizophrenia: possible role of anti-inflammatory medications in clinical and preclinical stages

AIMS

In this paper, we review the literature on the efficacy of anti-inflammatory agents as neuroprotectors in clinical and preclinical stages of schizophrenia.

METHOD

A synthetic and integrative approach was applied to review studies stemming from epidemiology, phenomenology, cognition, genetics and neuroimaging data. We provide conclusions and future directions of research on early-onset schizophrenia.

RESULTS

Abnormal inflammatory activation has been demonstrated in schizophrenia. Increases or imbalances in cytokines before birth or during childhood may impact neurodevelopment and produce vulnerability to schizophrenia. The specificity of inflammatory abnormalities in psychiatric disorders is controversial. Similar increases in pro-inflammatory cytokines have been described in other disorders, especially mood and anxiety disorders. One of the most important challenges at this point is the understanding of neurobiological correlates of prodromal stages of schizophrenia.

CONCLUSION

Although future research should investigate the exact role of different cytokines in pathophysiology of schizophrenia, these mediators emerge as promising molecular targets to its prevention and treatment.

Tumor necrosis factor alpha -308 gene locus promoter polymorphism: an analysis of association with health and disease

Tumor necrosis factor-alpha (TNF-alpha) is a potent immunomediator and proinflammatory cytokine that has been implicated in the pathogenesis of a large number of human diseases. The location of its gene within major histocompatibility complex and biological activities has raised the possibility that polymorphisms within this locus may contribute to the pathogenesis of wide range of autoimmune and infectious diseases. For example, a bi-allelic single nucleotide substitution of G (TNFA1 allele) with A (TNFA2 allele) polymorphism at -308 nucleotides upstream from the transcription initiation site in the TNF-alpha promoter is associated with elevated TNF-alpha levels and disease susceptibilities. However, it is still unclear whether TNF-alpha -308 polymorphism plays a part in the disease process, in particular whether it could affect transcription factor binding and in turn influence TNF-alpha transcription and synthesis. Several studies have suggested that TNFA2 allele is significantly linked with the high TNF-alpha-producing autoimmune MHC haplotype HLA-A1, B8, DR3, with elevated serum TNF-alpha levels and a more severe outcome in diseases. This review discusses the genetics of the TNF-alpha -308 polymorphism in selected major diseases and evaluates its common role in health and disease.

Association of blood levels of C-reactive protein with clinical phenotypes in Arab schizophrenic patients

Schizophrenia may be associated with inflammatory reactions and C-reactive protein (CRP) is a nonspecific serum protein marker for persisting inflammatory states. This study aimed to assess concentrations of high sensitivity CRP (hsCRP) in schizophrenic Arab patients and evaluate the relationships of hsCRP levels with aspects of clinical phenotypes of the disease. Two age-matched groups of subjects were studied: (1) healthy controls, HC, n=165; (2) patients with schizophrenia, SZ: n=207. Each subject was evaluated with a standard questionnaire for age at disease onset, family history, disease severity and outcome. Serum hsCRP levels were measured by immunoassay. The two groups of subjects were similar in age, ethnic composition and socioeconomic status. Those with SZ had significantly greater serum concentrations of hsCRP. There were significant associations between hsCRP and (i) age in both groups; (ii) body mass index (BMI) in HC but not in SZ. In the latter, hsCRP levels were: (a) marginally higher in women with later age of disease onset; (ii) highest with remission and with catatonic features; and (iii) lower with family history of psychosis. The study concludes that serum levels of hsCRP are increased in clinically stable Arab patients with schizophrenia and appear related to the disorder's clinical expression. It is suggested that there may be an inflammatory component to schizophrenia which is associated with aspects of its clinical phenotype.

TNF-alpha polymorphisms are associated with obsessive-compulsive disorder

INTRODUCTION

Several lines of evidence support an immunologic involvement in obsessive-compulsive disorder (OCD): the increased prevalence of OCD in patients with rheumatic fever (RF), and the aggregation of obsessive-compulsive spectrum disorders among relatives of RF probands. Tumor necrosis factor alpha is a proinflammatory cytokine involved in RF and other autoimmune diseases. Polymorphisms in the promoter region of the TNFA gene have been associated with RF. Given the association between OCD and RF, the goal of the present study was to investigate a possible association between polymorphisms within the promoter region of TNFA and OCD.

MATERIALS AND METHODS

Two polymorphisms were investigated: -308 G/A and -238 G/A. The allelic and genotypic frequencies of these polymorphisms were examined in 111 patients who fulfilled DSM-IV criteria for OCD and compared with the frequencies in 250 controls.

RESULTS

Significant associations were observed between both polymorphisms and OCD. For -238 G/A, an association between the A allele and OCD was observed (chi(2)=12.05, p=0.0005). A significant association was also observed between the A allele of the -308 G/A polymorphism and OCD (chi(2)=7.09, p=0.007). Finally, a haplotype consisting of genotypes of these two markers was also examined. Significant association was observed for the A-A haplotype (p=0.0099 after correcting for multiple testing).

DISCUSSION

There is association between the -308 G/A and -238 G/A TNFA polymorphisms and OCD in our Brazilian sample. However, these results need to be replicated in larger samples collected from different populations.

No association between the tumor necrosis factor-alpha gene promoter polymorphisms and schizophrenia in a Japanese population

Tumor necrosis factor-alpha (TNF-alpha) is a pleiotrophic cytokine and exerts neuroprotective and neurodegenerative effects in brain. Several studies have indicated that TNF-alpha is likely related to the pathogenesis of schizophrenia. Recent genetic investigations have revealed that a TNF-alpha gene promoter polymorphism (-G308A) is associated with schizophrenia, although negative findings have also been reported. To assess whether the TNF-alpha gene promoter variants including -G308A could be implicated in vulnerability to schizophrenia, we conducted a case-control association analysis (265 cases and 424 controls) and the transmission disequilibrium test (TDT) analysis (83 trios) for four polymorphisms (-G238A, -G308A, -C857T and -T1031C) in Japanese subjects. In a case-control analysis, there was no significant association between the promoter polymorphisms or haplotypes in the TNF-alpha gene and schizophrenia. In the TDT analysis, we also did not observe transmission distortion. Our results suggest that the above four polymorphisms in the promoter region of the TNF-alpha gene appear not to confer increased susceptibility for schizophrenia in a Japanese population.

-G308A tumor necrosis factor alpha functional polymorphism and schizophrenia risk: meta-analysis plus association study

Research on -G308A functional polymorphism in the tumor necrosis factor alpha (TNFalpha) gene as a susceptibility factor for schizophrenia has provided contrasting results in different populations. Therefore we conducted a meta-analysis of the published case-control association studies and a replication study in a large sample. Meta-analyses (total sample: 2512 cases versus 3223 controls) showed that the AA genotype was weakly associated with schizophrenia susceptibility in Caucasoids (Odd Ratio OR=1.65, 95% CI=1.00-2.71 Z=1.98 p=0.05). The replication case-control association study (323 DSM-IV-TR schizophrenia patients and 346 controls) showed that the A allele conferred an increased susceptibility for schizophrenia only in males (OR=1.73, 95% CI=1.07-2.79, p=0.025), and the association became more specific when only patients of the paranoid subtype were compared to the controls (relative risk ratio=3.09, 95% CI=1.28-7.47, p=0.012). The presence of the A allele was also associated with a later age at onset of schizophrenia in the whole sample (F(1,291)=7.094, p=0.008). Our results confirm that TNFalpha A allele could have an effect on vulnerability to schizophrenia but further studies revaluating the role of gender and diagnostic subtypes are necessary to confirm these findings.

Evaluation of association of SNPs in the TNF alpha gene region with schizophrenia

The association of the tumor necrosis factor alpha (TNFalpha) -G308A promoter polymorphism with schizophrenia has complemented clinical findings of increased levels of the TNFalpha cytokine in schizophrenic patients, with some support for a functional consequence of the variant. Our previous studies of genetic causes in schizophrenia supported findings of linkage to the major histocompatibility complex (MHC) region where the TNFalpha gene is located as well as association with the -G308A promoter polymorphism. While the common G-allele shows association in our sample, association with the A-allele has been reported by other groups. This suggests linkage disequilibrium (LD) rather than direct involvement in the disorder. In order to define LD of DNA variants with the disorder in this area, we analyzed 36 SNPs in a 165-kb region around this polymorphism. We detected nominally significant associations (P < 0.05) of three markers (including the -G308A promoter polymorphism) and multiple haplotypes with schizophrenia in our sample of 204 families (79 sib-pairs and 125 trios). The association is largely restricted to a 30 kb high LD region/block and should assist in the identification of a schizophrenia susceptibility gene within the block or elsewhere in the MHC.

Family and case-control association study of the tumor necrosis factor-alpha (TNF-alpha) gene with schizophrenia and response to antipsychotic medication

BACKGROUND

Dysregulation of the immune system has been suggested to play a role in the etiology of schizophrenia (SCZ). In this context, the tumor necrosis factor-alpha (TNF-alpha) is considered an interesting candidate for genetic studies as overproduction of TNF-alpha, which may be genetically modulated, can influence neuron growth and proliferation. Moreover, the TNF-alpha gene is located on chromosome 6p21.3, a region that has been found to be associated with SCZ in numerous linkage studies. One functional polymorphism, G-308A, has been studied for association with SCZ yielding inconsistent findings.

RESULTS AND DISCUSSIONS

In our study, we investigated the G-308A polymorphism with SCZ including 95 nuclear families and 149 pairs of cases/controls matched by age, gender, and ethnicity. Furthermore, we examined BPRS change scores (after 6 weeks, 3 months, and 6 months) and weight changes (after 6 weeks) with this polymorphism in 153 and 247 patients, respectively, after clozapine treatment. We did not observe biased transmission using family-based association test (P=0.752) or significant differences in case/control studies (P=0.839). However, patients with allele A showed significant improvement on BPRS change score after 3 months (t=2.000, P=0.049) and 6 months (t=2.481, P=0.015) of clozapine treatment when compared with patients without allele A. Moreover, trends were observed for genotype A/A with clinical improvement in BPRS change score after 6 months (F=2.834, P=0.065) using ANCOVA, and for allele G with weight gain (t=-1.702, P=0.091).

CONCLUSION

Overall, the G-308A polymorphism of the TNF-alpha gene does not appear to play a major role in SCZ but might be involved in antipsychotic response.

Interaction analysis between 5-HTTLPR and TNFA −238/−308 polymorphisms in schizophrenia

This study investigated the potential interaction between the polymorphisms of serotonin transporter gene (SLC6A4, a 44 base pair insertion/deletion in the promoter region, 5-HTTLPR) and tumor necrosis factor-alpha gene (TNFA; -238G/A and -308G/A polymorphisms) on the development of schizophrenia, as well as the interaction of the three polymorphisms in relation to symptomatology, family history, onset age and antipsychotic treatment response. Genomic DNA analyses with polymerase chain reaction (PCR) was used for the genotyping. One hundred and fifty-two (152) patients with schizophrenia and 152 normal controls participated in the study. Any associations between the individual polymorphism and schizophrenia were not found. However, marginal association between subjects with both TNFA -238 A allele (genotype AA plus AG) and 5-HTTLPR s allele (ss plus sl) and presence of family history was found (p = 0.023; p = 0.026). The subjects with TNFA -308 AG genotype showed higher change in PANSS total score (p = 0.028). No significant interaction effect between 5-HTTLPR and TNFA -238/-308 polymorphisms either on the development of schizophrenia or on antipsychotics treatment response and psychopathology was found, although a significant interaction effect for subjects carrying TNFA -238 AG and -308 AA genotypes on a positive family history was observed (p = 0.017). These results suggest that the interaction effects between 5-HTTLPR and TNFA -238/-308 polymorphisms gives no significant contribution to the susceptibility to schizophrenia, and is not associated with clinical variables, antipsychotic treatment response and psychopathological features, except for family history of disease, at least in the Korean population.

Tumor necrosis factor-alpha −G308A polymorphism in schizophrenia in a Finnish population

Tumor necrosis factor-alpha (TNF-alpha) is a proinflammatory cytokine with functions in nerve cell growth, differentiation, and apoptosis. There are several studies showing that a TNF-alpha--G308A promoter polymorphism, which possibly affects TNF-alpha transcription, is associated with schizophrenia, although negative results also exist. Our aim was to investigate the relationship between the TNF-alpha --G308A promoter polymorphism, the risk of schizophrenia, and the age of onset of schizophrenia, and the TNF-alpha -G308A polymorphism was therefore studied in 149 southern Finnish patients with a DSM-IV diagnosis of schizophrenia and in 393 healthy controls. The allele and genotype frequencies did not differ significantly between the patient and control groups (P=0.10 and 0.12, respectively), but the frequency of G/G homozygotes was statistically significantly higher in male patients than in male controls (chi(2)=5.03, d.f.=1, P=0.025) with an odds ratio of 2.00 (95% confidence interval: 1.08--3.70). No such difference was seen in female patients (P=0.79) or in the whole study group (P=0.064). The age of onset of schizophrenia did not differ significantly between the different TNF-alpha genotypes (ANOVA: F=0.45, P=0.64). In conclusion, we did not find a clear association between the TNF-alpha --G308A polymorphism and schizophrenia in the whole study group. However, TNF-alpha --G308A G/G homozygosity was modestly associated with schizophrenia in male patients.

Interaction of tumor necrosis alpha - G308A and epidermal growth factor gene polymorphisms in early-onset schizophrenia

The study population comprised 94 Finnish patients with DSM-IV diagnosis of schizophrenia. The patients were placed into two subgroups according to medication response to conventional neuroleptics. The aim of the study was to examine the frequency of tumor necrosis factor -308 (G > A) polymorphism in these patients and their 98 control subjects who were age- and gender-matched blood donors. Associations between TNFalpha -308 polymorphism alone and between the interaction of TNFalpha and epidermal growth factor gene polymorphisms, and medication response and age at onset of schizophrenia were also studied. The frequencies of TNFalpha A-allele were 11.7 % in patients and 12.8% in controls. The difference was not significant (p = 0.75). TNFalpha -308 polymorphism was not associated with medication response. However, patients with EGF AA and TNFalpha AG/AA genotype had a lower age at onset of schizophrenia compared with the rest of the patients not having this combination (20.0 years, 3.3 vs. 30.2 years, 10.1 mean + SD; p < 0.001). The results support earlier findings according to which TNFalpha polymorphism is not associated with the incidence of schizophrenia. On the other hand, the role of cytokines in schizophrenia may involve genetic interactions predisposing early onset of illness.

Queensland Centre for Mental Health Research: the first 17 years

OBJECTIVE

To reflect on the establishment and evolution of the Queensland Centre for Mental Health Research.

METHOD

Narrative historical review.

RESULTS

First established as an inpatient research unit in December 1987, the focus of the Centre evolved in concert with the skills of the staff. After the structure was revised in 1996 and 1999, the Centre has evolved into a group with four main research streams--epidemiology, developmental neurobiology, genetics and policy and economics. Although the group maintains a strong focus on serious mental disorders such as schizophrenia, our policy and economic work has a wider perspective. The Queensland Centre for Mental Health Research is based in an historic mental health service, with laboratories in collaborating universities and institutes. Key lessons learnt by the group along the way relate to the importance of focusing on a restricted range of research topics in order to build a critical mass.

CONCLUSIONS

Given a facilitating environment, hospital-based research groups can prosper. Over the last 17 years, a cost-efficient, focused and productive research group has evolved that has made contributions to international research.

Increased serum interleukin-1beta and interleukin-6 in elderly, chronic schizophrenic patients on stable antipsychotic medication

In schizophrenia, alterations of proinflammatory cytokine levels have been reported and related to the disease and psychopathology. However, only limited conclusions can be drawn in view of confounding factors such as infection, age, sex, smoking, and antipsychotic medication. Chronic schizophrenic patients with a long-term disease process and medication period have not been investigated so far. We have measured serum levels of interleukin (IL)-1beta, IL-6, and tumor necrosis factor (TNF)alpha in 41 elderly, chronic schizophrenic patients and 23 age- and sex-matched controls using enzyme-linked immunosorbent assay (ELISA). We assessed detailed psychopathology and neuropsychological performance and determined serum levels of haloperidol, clozapine, and the two main clozapine metabolites, desmethylclozapine and clozapine metabolite N-oxide, by high-pressure liquid chromatography (HPLC). IL-1beta and IL-6 levels were increased in treatment-resistant schizophrenic patients compared with healthy controls, whereas TNFalpha showed no difference. We did not find statistically significant differences of cytokine levels between medication groups and there was no correlation with serum levels of antipsychotics or psychopathological rating scores. Elevations of IL-1beta and IL-6 in elderly chronic schizophrenic patients may be related to an active disease process lasting until old age. Despite missing correlations, long-term treatment effects in treatment-resistant patients may have affected TNFalpha, leading to control levels. Post-mortem and animal studies should clarify the presence of altered immune function in the brain as well as the effect of cytokine levels in relation to neurodevelopmental disturbances and schizophrenia-associated behavior.

Tumor necrosis factor promoter haplotype associated with schizophrenia reveals a linked locus on 1q44

Using restriction fragment length polymorphism and pyrosequencing methods, we genotyped two TNFA gene promoter SNPs (-G308A, -G238A) and analyzed the haplotype structure in 24 Canadian families of primarily Celtic origin. Our results demonstrate that after correction for multiple testing based on simulations of 10 000 replicates of unlinked/unassociated data, there is evidence for association (P=0.026) of a specific haplotype (-308A, -238G) with schizophrenia and schizophrenia spectrum disorders with a family-based trimmed haplotype linkage disequilibrium test (Trimhap). Stratifying the 22 families with genome scan data by TNFA promoter haplotypes followed by reanalysis of linkage to schizophrenia throughout the genome, we identified few loci that exhibit a considerable increase in LOD/HLOD scores. A locus on chromosome 1q44 (D1S1609) demonstrated a significant increase (P=0.025) in LOD score from 0.15 to 3.01 with a broad definition of the schizophrenia phenotype and a dominant mode of inheritance. This result replicates a previously reported positive result of linkage of schizophrenia spectrum disorders to this area of the genome. We also illustrated that simulation studies are pivotal in evaluating the significance of results obtained with newer statistical methods, when multiple, but not independent, tests are performed, and when sample stratification is utilized to reduce the impact of heterogeneity or assess the interaction between loci.

No association between the promoter variants of tumor necrosis factor alpha (TNF-α) and schizophrenia in Chinese Han population

An increasing amount of evidence suggests that the pathophysiology of schizophrenia is associated with activation of the immune system. Four studies have established an association of -308G/A polymorphism of tumor necrosis factor alpha (TNF-alpha), a cytokine involved in inflammatory processes, with schizophrenia [Mol. Psychiatry 6 (2001) 79; Mol. Psychiatry 8 (2003) 718; Schizophr. Res. 65 (2003) 19; Biol. Psychiatry 54 (2003) 1205]. In the present study, however, no significant positive association has been found between any individual SNP or haplotype constituted of the five promoter polymorphisms (-1031T/C, -863C/A, -857C/T, -308G/A and -238G/A) in the human TNF-alpha gene and schizophrenia (314 Chinese Han schizophrenic patients and 340 healthy control). A meta-analysis we did in this work, which is based on previous nine studies plus our own unpublished data including a total of 2399 schizophrenic patients (sporadic cases 2099, familial cases >505) and more than 3261 controls, failed to show significant difference of -308G/A distribution between patients and controls in both the whole sample and the pooled Asian sample. By contraries, the significant results in the pooled Caucasian sample imply an ethnic heterogeneity in -308G/A variation in the TNF-alpha gene in schizophrenia.