Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0036341 (schizophrenia)
 60,220 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Susceptibility to autoimmunity is strongly influence by genes clustered in the MHC region, particularly class I and class II antigens. It has been proposed that there is an immune component in the aetiology of schizophrenia, and the distribution of human leukocyte antigens (HLA) in schizophrenic patients and controls has been investigated in numerous studies. Positive associations have been reported between schizophrenia and the HLA-A1, A2, A9, B5, Cw4, and DR8 and negative associations with HLA-DR4 and HLA-DQbeta*0602. Small sample size, variable diagnostic methodology, unreliable laboratory and statistical procedures, and possible mismatching of cases and controls may have contributed to a lack of consistency of results to date. Therefore, in this investigation we used a large and carefully diagnosed homogeneous Irish familial schizophrenic sample compared with ethnically matched controls. All alleles were determined using polymerase chain reaction amplification followed by short specific oligoprobes. We found no evidence of association with 80 HLA alleles (some previously not examined) from 4 genes. Our data therefore do not support the involvement of these classical HLA loci in the aetiology of schizophrenia at least in these Irish families. The remaining classical HLA loci (HLA-B and HLA-C) should be typed when reliable DNA-based methods become available.
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PMID:Schizophrenia and HLA: No association with PCR-SSOP typed classical loci in a large Irish familial sample. 1040 12

Linkage disequilibrium mapping of the MHC region in 80 British parent-offspring trios showed that NOTCH4 was highly associated with schizophrenia. The A-->G substitution in the promoter region and the (CTG)n repeat in exon 1 of NOTCH4 may be candidate sites conferring susceptibility to schizophrenia.
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PMID:The NOTCH4 locus is associated with susceptibility to schizophrenia. 1093 76

Evidence from epidemiological studies and segregation analysis suggests oligo- or polygenic inheritance in schizophrenia. Since model independent methods are thought to be most appropriate for linkage analysis in complex disorders, we performed a genome-wide autosomal screen in 71 families from Germany and Israel containing 86 independent affected sib-pairs with parental genotype information for statistical analysis strictly identity by descent. We genotyped 305 individuals with 463 markers at an average distance of approximately 10 cM genome-wide, and 1-2 cM in candidate regions (5q, 6p, q, 8p, 10p, 18p, 22q). The highest multipoint LOD scores (ASPEX) were obtained on 6p (D6S260, LOD = 2.0; D6S274, LOD = 2.2, MHC region, LOD = 2.15) and on 10p (D10S1714, LOD = 2.1), followed by 5q (D5S2066, LOD = 1.36), 6q (D6S271, LOD = 1.12; D6S1613, LOD = 1.11), 1q (D1S2675, LOD = 1.04), and 18p (broad disease model: D18S1116, LOD = 1.0). One hundred and thirty-three additional family members were available for some of the families (extended families) and were genotyped for these regions. GENEHUNTER produced a maximum NPL of 3.3 (P = 0.001) for the MHC region and NPL of 3.13 (P = 0.0015) for the region on 10p. There is support for these regions by independent groups. In genome-wide TDT analysis (sTDT, implemented in ASPEX), no marker passed the significance level of 0.0001 given by multiple testing, but nominal significance values for D10S211 (P = 0.03) and for GOLF (P = 0.0032) support further the linkage results on 10p and 18p. Our survey of 22 chromosomes identified candidate regions which should be useful to screen for schizophrenia susceptibility genes.
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PMID:A genome-wide autosomal screen for schizophrenia susceptibility loci in 71 families with affected siblings: support for loci on chromosome 10p and 6. 1112 94

The hypothesis that HLA antigens confer susceptibility to schizophrenic disorders has been tested by studying linkage and association in a family sample with 69 sib-pair families. Suggestive evidence for linkage was obtained by nonparametric multipoint LOD score analysis with a maximum around DQB CAR (P = 0.0004), a microsatellite marker that is in linkage disequilibrium with the HLA antigen DQB1. Spurious evidence for negative association as calculated by the transmission disequilibrium test was found for HLA- DRB1*11 (chi-square = 11.72, corrected P value = 0.03) and for the haplotype DQB1*301-DQA1*501-DRB1*11 (chi-square = 11.3, corrected P value = 0.043). No evidence of association with these alleles was obtained in a sample of 89 trios with schizophrenic offspring and parents. Our results are not in favor of a direct involvement of the HLA system in development of schizophrenia, but are compatible with the possible existence of a susceptibility gene in the MHC region at chromosome 6p 21.31.
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PMID:Investigation of linkage and association/linkage disequilibrium of HLA A-, DQA1-, DQB1-, and DRB1-alleles in 69 sib-pair- and 89 trio-families with schizophrenia. 1192 Aug 55

Mapping of disease susceptibility loci within the MHC has been partly hampered by the high degree of polymorphism of the HLA genes and the high level of linkage disequilibrium (LD) between markers within the MHC region. It is therefore important to identify new markers and determine the level of LD between HLA alleles and non-HLA genes. The NOTCH4 gene lies at the centromeric end of the MHC class III region, approximately 335 kb telomeric of the DRB1 locus. The encoded protein is an oncogene that is important in regulating vascular development and remodelling. A recent report has linked polymorphisms within NOTCH4 with risk of developing schizophrenia. We have investigated if coding polymorphisms exist within this gene and have identified three single nucleotide polymorphisms; a synonomous T to C transition at +1297 (HGBASE accession number SNP000064386), a synonomous A to G transition at +3061 (SNP000064387) and an A to G transition at +3063 which results in a replacement of glycine with aspartic acid at amino acid 279 (SNP000064388). The allele frequencies of +1297T, +3061A and +3063G were 0.65, 0.66 and 0.66, respectively. Linkage disequilibrium was detected both between these markers and with MHC alleles. These findings can be used in the fine mapping of disease susceptibility alleles within the MHC.
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PMID:Identification of novel single nucleotide polymorphisms within the NOTCH4 gene and determination of association with MHC alleles. 1264 76

Schizophrenia is a social disease that occurs in 0.5-1% of the population. It shows a high variability in both clinical picture and theory of its pathogenesis. Its clinical manifestations are accompanied by biochemical, immunological and structural changes. A pivotal role in the development of psychotic disorders is attributed to the impaired limbic system. The aim of this study was to find out whether, and if so, to what extent immunocompetent cells of the central nervous system (microglia) are involved in the process of degeneration occuring in these structures. The study was carried out on 12 brains of female chronic schizophrenics. Sections of frontal and temporal cortex were subjected to ultrastructural as well as histochemical and immunohistochemical examinations by light microscopy. In the structures under study, a large number of ramified microglial cells showing on their surface the expression of the major histocompatibility complex class II (MHC II) was observed. Most cells showed degenerative traits (cytoplasm shrinkage, thinning, shortening and fragmentation of their processes) up to apoptotic changes. Perivascular microglia displayed the lowest intensity of degenerative changes. Ultrastructurally, some damaged microglial cells contained phagosomes and/or degenerated mitochondria. Most abnormal microglia showed morphological signs of the former normal function of immunocompetent and phagocytosing cells. Degeneration of microgial cells, resulting most likely from the primary impairment of the neuron-glia communication that damages their immunocompetent function, may lead to the exacerbation of structural damage and psychotic symptoms. Treatment of chronic schizophrenics should involve the supply of agents to prevent degeneration of microglia and/or long-term immunotherapy.
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PMID:Degeneration of microglial cells in frontal and temporal lobes of chronic schizophrenics. 1553 34

Schizophrenia affects 1% of the world's population, but its cause remains obscure. Numerous theories have been proposed regarding the cause of schizophrenia, ranging from developmental or neurodegenerative processes or neurotransmitter abnormalities to infectious or autoimmune processes. In this review, findings suggestive of immune dysregulation and reactivity to self in patients with schizophrenia are examined with reference to criteria for defining whether or not a human disease is autoimmune in origin. Associations with other autoimmune diseases and particular MHC haplotypes, increased serum levels of autoantibodies, and in vivo and in vitro replication of some of the functional and ultrastructural abnormalities of schizophrenia by transfer of autoantibodies from the sera of patients with schizophrenia suggest that, in some patients at least, autoimmune mechanisms could play a role in the development of disease. Recent findings regarding specific autoimmune responses directed against neurotransmitter receptors in the brain in patients with schizophrenia will also be reviewed.
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PMID:Immune dysregulation and self-reactivity in schizophrenia: do some cases of schizophrenia have an autoimmune basis? 1566 Oct 36

Schizophrenia is a mind-destructive disease. Family and twin studies have indicated an equal contribution of genetic endowment and environmental factors in the pathogenesis of schizophrenia. Recently Chlamydiaceae species has been identified as a major factor in the pathogenesis of schizophrenia, suggesting defective immune responses of schizophrenic patients against this environmental factor. Immune responses against Chlamydiaceae species are controlled by immunogenetic factors. Successful responses against microbes depend on the presentation of immunogenic peptides by HLA molecules, which are encoded by a highly polymorphic gene system. Until now several HLA alleles or HLA antigens have been found associated with schizophrenia by some researchers but not by others. This could be explained by failing immune responses against different microbes or different immune responses against the same microbe. Another explanation, not contradictory rather supplementary, is the participation of non-classical HLA genes in the immune response and thus in the disease development. Variants of these genes, i.e. alleles, which control transportation and loading of microbial peptides onto HLA molecules, could prevent clearing of immune cell infection by selection of non-immunogenic peptides for HLA presentation. To generate support for our hypothesis we determined in a small group of schizophrenic patients and control individuals allele frequencies of the transporter proteins TAP1/TAP2, which select the immunoproteasome-tailored peptides for transportation. We determined also frequencies of TAPASIN alleles, which encode chaperons and also may select peptides for loading on MHC molecules. Our pilot study included 20 patients and 162 control individuals. We found significant associations between schizophrenia and TAP1 allele frequencies (P=9.95x10(-3), chi(2)=12.36) as well as TAPASIN allele frequencies (P=2.8x10(-2), chi(2)=5.3). This suggests that variants of these two genetic systems could influence the disease process of schizophrenia. Furthermore, these genes belong to the family of ABC transporter proteins and may also influence the efficiency of drugs and thus of therapeutic modalities. Our investigations require certainly larger patient panels to prove our hypothesis and our results to be correct.
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PMID:Transporter associated with antigen processing and the chaperone tapasin: are non-classical HLA genes keys to the pathogenesis of schizophrenia? 1921 16

A link between celiac disease and schizophrenia has been postulated for several years, based primarily on reports of elevated levels of antibody to gliadin in patients. We sought to examine the proposed connection between schizophrenia and celiac disease by characterizing the molecular specificity and mechanism of the anti-gliadin immune response in a subset of individuals with schizophrenia. Blood samples from individuals with schizophrenia and elevated anti-gliadin antibody titer were examined for celiac disease-associated biomarkers, including antibodies to transglutaminase 2 (TG2) enzyme and deamidated gliadin peptides, as well as the HLA-DQ2 and -DQ8 MHC genes. The anti-gliadin antibody response was further characterized through examination of reactivity towards chromatographically separated gluten proteins. Target proteins of interest were identified by peptide mass mapping. In contrast to celiac disease patients, an association between the anti-gliadin immune response and anti-TG2 antibody or HLA-DQ2 and -DQ8 markers was not found in individuals with schizophrenia. In addition, the majority of individuals with schizophrenia and anti-gliadin antibody did not exhibit antibody reactivity to deamidated gliadin peptides. Further characterization of the antibody specificity revealed preferential reactivity towards different gluten proteins in the schizophrenia and celiac disease groups. These findings indicate that the anti-gliadin immune response in schizophrenia has a different antigenic specificity from that in celiac disease and is independent of the action of transglutaminase enzyme and HLA-DQ2/DQ8. Meanwhile, the presence of elevated levels of antibodies to specific gluten proteins points to shared immunologic abnormalities in a subset of schizophrenia patients. Further characterization and understanding of the immune response to gluten in schizophrenia may provide novel insights into the etiopathogenesis of specific disease phenotypes.
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PMID:Novel immune response to gluten in individuals with schizophrenia. 1974 29

Common variant single-nucleotide polymorphisms at the MHC locus have recently been associated with schizophrenia. Together with known associations with rare copy-number variants affecting many genes, this reveals the highly polygenic etiology of the disease.
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PMID:Common variants in polygenic schizophrenia. 1978 21


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