Search for schizophrenia susceptibility variants at the HLA-DRB1 locus among a British population

Association of NOTCH4 and CYP2E1 Genetic Variants With Schizophrenia in the Bangladeshi Population: A Case-Control Study

Background and Aims

Schizophrenia (SCZ) is among the most persistent and devastating psychological problems. Different genetic polymorphisms are responsible for the predisposition of SCZ, and we screened NOTCH4 (rs2071287, rs204993) and CYP2E1 (rs2070673) polymorphisms in this study to find the connection with SCZ development.

Methods

We investigated a total of 420 samples (210 patients and 210 controls) and used the PCR-RFLP technique to genotype all SNPs. For statistical analyses, SPSS (version 25.0) was applied.

Results

In the case of NOTCH4 rs2071287, no evidence of a link was found in any genetic models, whereas NOTCH4 rs204993 and CYP2E1 rs2070673 showed a significant linkage in four genetic models with SCZ risk (for NOTCH4 rs204993, additive model 2: OR = 3.39, CI = 1.84-6.23, p = 0.0001; dominant: OR = 1.84, CI = 1.22-2.76, p = 0.0032; recessive: OR = 2.67, CI = 1.53-4.64, p = 0.0005; allelic: OR = 1.75, CI = 1.32-2.30, p = 0.0001 and for CYP2E1 rs2070673, additive model 2: OR = 0.39, CI = 0.22-0.69, p = 0.0013; recessive: OR = 0.45, CI = 0.29-0.68, p = 0.0002; overdominant: OR = 1.49, CI = 1.02-2.19, p = 0.0408; allelic: OR = 0.61, CI = 0.46-0.80, p = 0.0004).

Conclusions

The findings of our study suggest that the polymorphisms NOTCH4 rs204993 and CYP2E1 rs2070673 in the Bangladeshi ethnicity are connected to the risk of SCZ.

No correlation between HLA-DQ 2.5, DQ 8.1 and DQ 6.2 and circulating levels of antibodies against gliadins in schizophrenia

It has been suggested that gluten consumption is linked to schizophrenia, with this link strengthened through the presence of circulating anti-native gliadin antibodies (AGAs). The human leukocyte antigen (HLA) system is crucial for antigen presentation and antibody secretion but no study has examined the relationship between HLA-II variants and circulating antibodies against gliadin peptides. In this study, HLA-II variants were genotyped in patients with schizophrenia and the relationship between these variants and plasma AGA levels was examined. Although there was no association found, HLA-AGA associations could potentially serve as a marker of gluten sensitivity in patients with schizophrenia.

GPX1 Pro198Leu polymorphism and GSTP1 Ile105Val polymorphisms are not associated with the risk of schizophrenia in the Chinese Han population

Increasing lines of evidence show that oxidative stress plays a role in the pathophysiological mechanisms of schizophrenia (SCZ). Polymorphic variants of oxidative stress-related candidate genes GPX1 and GST1 can affect the antioxidant activities of their encoded enzymes. Therefore, this study aimed to explore the association between the single nucleotide polymorphisms (SNPs) of GPX1 and GSTP1 and susceptibility to schizophrenia in the Chinese Han population. DNA from 323 healthy controls and 210 schizophrenic patients was genotyped for SNPs rs1050450 in GPX1 and rs1695 in GSTP1 using a predesigned TaqMan SNP genotyping assay. Differences in genetic distributions between cases and controls were compared using the χ-test. No significant differences in allelic or genotypic frequencies of GPX1 rs1050450 or GSTP1 rs1695 were detected between cases and controls (GPX1 rs1050450: χ=0.370, P=0.831 by genotype, χ=0.377, P=0.539, odds ratio=1.145, 95% confidence interval=0.743-1.766 by allele; GSTP1 rs1695: χ=1.537, P=0.464 by genotype, χ=1.623, P=0.203, odds ratio=0.813, 95% confidence interval=0.592-1.118 by allele). Our results suggest that GPX1 rs1050450 and GSTP1 rs1695 SNPs are unlikely to play a major role in the pathogenesis of schizophrenia in the Chinese Han population. However, these results should be validated by replication in larger and independent samples.

Association of the NOTCH4 Gene Polymorphism rs204993 with Schizophrenia in the Chinese Han Population

NOTCH4 regulates signaling pathways associated with neuronal maturation, a process involved in the development and patterning of the central nervous system. The NOTCH4 gene has also been identified as a possible susceptibility gene for schizophrenia (SCZ). The objective of this study was to examine the relationship between NOTCH4 polymorphisms and SCZ in the Chinese Han population. The rs2071287 and rs204993 polymorphisms of the NOTCH4 gene were analyzed in 443 patients with SCZ and 628 controls of Han Chinese descent. Single SNP allele-, genotype-, and gender-specific associations were analyzed using different models (i.e., additive, dominant, and recessive models). This association study revealed that the rs204993 polymorphism is significantly associated with susceptibility for SCZ and that the AA genotype of rs204993 is associated with a higher risk for SCZ (P = 0.027; OR = 1.460; 95% CI, 1.043–2.054). Our data are consistent with those obtained in previous studies that suggested that rs204993 is associated with SCZ and that the AA genotype of rs204993 demonstrates a higher risk. Further large-scale association analyses in Han Chinese populations are warranted.

Association of HLA-DR/DQ polymorphisms with schizophrenia in Tunisian patients

BACKGROUND AND OBJECTIVES

The hypothesis that human leukocyte antigens (HLAs) confer susceptibility to schizophrenic disorders has been tested by studying linkage and association in family samples. Our goal was to evaluate the role of HLA in the risk of developing schizophrenia in a Tunisian population.

DESIGN AND SETTINGS

Blood samples for this case-control study were collected from patients of the Department of Psychiatry at the Military Hospital of Tunisia between July 2012 and May 2013.

METHODS

A total of 140 patients with schizophrenia were recruited for genetic analysis. Controls included 100 persons matched for age, sex, and risk factors. Participants were tested for HLA class II alleles. HLA-DRB1 and HLA-DQB1 alleles were genotyped using polymerase chain reaction sequence-specific primers.

RESULTS

This study indicates that the alleles most responsible for disease susceptibility are DRB1*03 (P < 10-3) and DQB1*02 (P < 10-3) (P denotes probability values). The most protective alleles are DRB1*13 (P=.013) and DQB1*05 (P < 10-3). Further results revealed that DRB1*0301/DQB1*0201(P < 10-3), DRB1*0401/DQB1*0301 (P < 10-3) and DRB1*1101/DQB1*0301 (P < 10-3) are haplotypes most conducive to disease susceptibility.

CONCLUSION

The present findings support an association between schizophrenia and the HLA-DR-DQ locus among a Tunisian population. To our knowledge, this is the first study performed to analyze the association of HLA DRB1/DQB1 alleles on schizophrenia susceptibility in Tunisia.

Association between the NOTCH4 gene rs3131296 polymorphism with schizophrenia risk in the Chinese Zhuang population and Chinese Han population

BACKGROUND

Schizophrenia (SZ) is a common severe psychiatric disorder and a complex polygenic inherited disease that has not yet been fully interpreted. Heredity was proven to play an important role in the development of SZ. The association between the NOTCH4 gene rs3131296 polymorphism and SZ was reported to reach significance at the genome-wide level; therefore, it is necessary to replicate this association in other different populations.

METHODS

To evaluate the association of the NOTCH4 gene rs3131296 polymorphism with the risk for SZ, and to explore whether a significant association could be replicated in different ethnic groups of China, we conducted this case-control study on 282 SZ cases (188 Han and 94 Zhuang) and 282 controls (188 Han and 94 Zhuang) among the Chinese Zhuang and Han populations.

RESULTS

The results showed no statistically significant difference in the genotype or allele frequencies of the NOTCH4 gene variant rs3131296 between SZ patients and healthy controls in either the Zhuang or Han samples (p > 0.05). In addition, no significant difference was found in genotype or allele frequencies of the NOTCH4 gene variant rs3131296 between cases and controls in the combined samples including Zhuang and Han samples.

CONCLUSIONS

Our study failed to replicate the significant association between the NOTCH4 gene rs3131296 polymorphism and the risk for SZ.