Association study of a functional promoter polymorphism in the XBP1 gene and schizophrenia.код для вставкиСкачать
American Journal of Medical Genetics Part B (Neuropsychiatric Genetics) 141B:71 –75 (2006) Association Study of a Functional Promoter Polymorphism in the XBP1 Gene and Schizophrenia Erik G. Jönsson,1* Sven Cichon,2,3 Johannes Schumacher,2 Rami Abou Jamra,2 Thomas G. Schulze,4 Monica Deschner,4 Kaj Forslund,1 Håkan Hall,1 Peter Propping,2 Piotr M. Czerski,5 Monica Dmitrak-Weglarz,5 Pawel Kapelski,5 Martin Driessen,6 Wolfgang Maier,7 Joanna Hauser,5 Marcella Rietschel,4 and Markus M. Nöthen2,3 1 Department of Clinical Neuroscience, Psychiatry Section, R5:00, Karolinska Institutet, Stockholm, Sweden Institute of Human Genetics, University of Bonn, Bonn, Germany 3 Life & Brain Center, University of Bonn, Bonn, Germany 4 Division of Genetic Epidemiology in Psychiatry, Central Institute of Mental Health, Mannheim, Germany 5 Department of Adult Psychiatry, Poznan University of Medical Sciences, Poznan, Poland 6 Department of Psychiatry, Gilead Hospital, v. Bodelschwingsche Anstalten Bethel, Bielefeld, Germany 7 Department of Psychiatry, University of Bonn, Bonn, Germany 2 A functional promoter polymorphism (116C/G) of the X-box binding protein 1 gene (XBP1) gene was reported to be associated with schizophrenia in Asian subjects. In a replication attempt, three European case-control samples comprising 2,182 German, Polish, and Swedish subjects, were genotyped for the XBP1 116C/G polymorphism. Allele and genotype frequencies were compared between schizophrenic patients and control subjects. There were no significant case-control differences in any of the three samples, although in a meta-analysis with previous results comprising 3,612 subjects there was a borderline association between the 116G-containing genotypes and schizophrenia. We conclude that the functional XBP1 gene polymorphism is not of major importance to schizophrenia in the European populations investigated. It cannot be excluded, however, that the XBP1 polymorphism is involved in schizophrenia in other populations or adds minor susceptibility to the disorder. ß 2005 Wiley-Liss, Inc. KEY WORDS: X-box binding protein 1 gene (XBP1); case-control association study; bipolar disorder; metaanalysis INTRODUCTION Family, twin, and adoption studies suggest that genetic factors play a role in the etiology of schizophrenia [McGuffin Grant sponsor: Fund for Scientific Research Flanders; Grant sponsor: National Genomic Network of the German Ministry of Education and Research; Grant sponsor: Deutsche Forschungsgemeinschaft; Grant sponsor: Polish State Committee for Scientific Research; Grant sponsor: Swedish Research Council; Grant number: 5454þK2004-21X-15078-01A; Grant sponsor: Söderström–Königska Foundation; Grant sponsor: Wallenberg Foundation; Grant sponsor: HUBIN Project. *Correspondence to: Erik G. Jönsson, Department of Clinical Neuroscience, Psychiatry Section, R5:00, Karolinska Institutet, SE-171 76 Stockholm, Sweden. E-mail: firstname.lastname@example.org Received 15 June 2005; Accepted 21 October 2005 DOI 10.1002/ajmg.b.30262 ß 2005 Wiley-Liss, Inc. et al., 2002]. Recently, several suggestive and promising associations between different gene variants and the disorder have been reported, although evidence for functionally relevant susceptibility variants is still lacking [Craddock et al., 2005; Harrison and Weinberger, 2005]. The X-box binding protein 1 gene (XBP1) is a pivotal gene involved in a complex cascade of events in the stress response of the endoplasmatic reticulum. Recently, a C to G substitution at position 116 in the XBP1 gene was shown to lead to a loss of the binding motif of the gene, which subsequently impaired the XBP1 loop in the endoplasmatic reticulum’s stress response [Kakiuchi et al., 2003]. The XBP1 116C/G polymorphism was also associated with bipolar disorder [Kakiuchi et al., 2003], although recently the genetic evidence has been challenged [Cichon et al., 2004; Hou et al., 2004]. Bipolar disorder and schizophrenia are usually treated as separate disorders. However, there are difficulties to draw clear borders between the syndromes. There are several reports of families where both disorders segregate [St. Clair et al., 1990]. Subjects with the same genetic makeup have been diagnosed with each of the two syndromes [McGuffin et al., 1982], and evidence for both common and shared genetic contributions of the two disorders have been reported [Cardno et al., 2002]. All this has challenged the dual Kraepelinian way of looking at bipolar disorder and schizophrenia and it has been suggested that the disorders rather constitute different points in a continuum of psychosis [Crow, 1990]. The XBP1 gene is located on chromosome 22q12 [Liou et al., 1991], one of several areas where claim for linkage has been reported in both bipolar and schizophrenic families [Riley and McGuffin, 2000]. As a consequence, the XBP1 116C/G polymorphism has also been investigated in schizophrenia and association was reported in two Asian studies [Chen et al., 2004; Kakiuchi et al., 2004]. In a replication attempt, we investigated the functional promoter XBP1 polymorphism for association with schizophrenia in German, Polish, and Swedish cases and controls. MATERIALS AND METHODS Subjects The study was performed in accordance with the Code of Ethics of the World Medical Association (Declaration of Helsinki) and approved by the ethical committees in each of the participating centers (Bonn, Mannheim, Poznan, and Stockholm). All subjects participated after giving informed consent. Subjects have been previously described [Van Den Bogaert et al., 2003]. They consisted of patients fulfilling 252 403 115 126 64 60 106 191 178 144 258 349 131 117 43 55 111 195 148 173 G/G G/C 45 64 27 39 15 19 17 65 48 54 C/C Genotype (counts) OR, odds ratio; CI, confidence interval. a 2 w ¼ 5.20, degree of freedom (df) ¼ 1, P < 0.05. Heterogeneity w2 ¼ 1.18, df ¼ 1, not significant (NS). b 2 w ¼ 4.64, df ¼ 1, P < 0.05. Heterogeneity w2 ¼ 3.02, df ¼ 1, NS. c 2 w ¼ 7.97, df ¼ 1, P < 0.01. Heterogeneity w2 ¼ 0.00, df ¼ 1, NS. d 2 w ¼ 1.05, df ¼ 1, NS. Heterogeneity w2 ¼ 2.92, df ¼ 2, NS. e 2 w ¼ 0.71, df ¼ 1, NS. Heterogeneity w2 ¼ 1.56, df ¼ 2, NS. f 2 w ¼ 0.16, df ¼ 1, NS. Heterogeneity w2 ¼ 2.65, df ¼ 2, NS. g 2 w ¼ 0.38, df ¼ 1, NS. Heterogeneity w2 ¼ 9.97, df ¼ 4, P < 0.05. h 2 w ¼ 4.18, df ¼ 1, P < 0.05. Heterogeneity w2 ¼ 5.74, df ¼ 4, NS. i 2 w ¼ 2.16, df ¼ 1, NS. Heterogeneity w2 ¼ 8.61, df ¼ 4, NS. Total Total European Present study Present study Present study Total Asian Chen et al.  N Patients 234 Controls 451 Shanghai, China; Patients 374 Han Chinese Controls 371 Patients 608 Controls 822 Bonn, Mannheim, Patients 555 Germany; Caucasian Controls 816 Poznan, Poland; Caucasian Patients 273 Controls 282 Stockholm, Sweden; Caucasian Patients 122 Controls 134 Patients 950 Controls 1,232 Patients 1,558 Controls 2,054 Subjects’ residence; ethnicity Kakiuchi et al.  Tokyo, Japan; Japanese References Subject category 0.83–2.23 0.77–1.08 0.91–1.19 0.91d 1.04g 0.64–1.26 1.36 0.90 0.69–1.06 1.04–1.59 1.28a 0.85 1.07–1.92 0.82–1.55 95% CI 1.43 1.13 OR G/G versus (G/CþC/C) 1.26h 1.13e 1.18 1.46 0.96 1.44b 1.16 2.15 OR 1.01–1.57 0.85–1.51 0.57–2.44 0.87–2.46 0.65–1.44 1.03–2.02 0.76–1.76 1.23–3.76 95% CI (G/GþG/C) versus C/C TABLE I. XBP1 116C/G Polymorphism and Schizophrenia: Meta-Analysis of Association Studies 69 71 66 65 70 65 69 64 67 62 G allele frequency (%) 95% CI 1.08i 0.98–1.19 0.97f 0.86–1.11 1.24 0.86–4.81 1.03 0.80–1.32 0.90 0.77–1.07 1.26c 1.07–1.47 1.26 1.02–1.56 1.25 0.99–1.59 OR G versus C allele Patients Control Patients Controls Patients Controls Patients Controls Patients Controls Patients Controls Subject category Patients Controls Patients Controls Patients Controls Patients Controls Patients Controls Patients Controls Subject category 307 411 160 109 75 73 542 593 224 197 766 790 N w ¼ 0.98, df ¼ 1, NS. Heterogeneity w2 ¼ 8.06, df ¼ 2, P < 0.02. w ¼ 0.39, df ¼ 1, NS. Heterogeneity w2 ¼ 0.35, df ¼ 2, NS. c 2 w ¼ 0.21, df ¼ 1, NS. Heterogeneity w2 ¼ 4.46, df ¼ 2, NS. d 2 w ¼ 0.16, df ¼ 1, NS. Heterogeneity w2 ¼ 14.61, df ¼ 3, P < 0.01. e 2 w ¼ 0.67, df ¼ 1, NS. Heterogeneity w2 ¼ 0.35, df ¼ 3, NS. f 2 w ¼ 0.48, df ¼ 1, NS. Heterogeneity w2 ¼ 8.31, df ¼ 3, P < 0.05 b 2 a 2 Total Chen et al.  Present study, total Present study, Sweden Present study, Poland Present study, Germany References 248 405 113 173 47 61 408 639 150 174 558 813 N 69 71 122 203 47 73 20 31 G/G 63 79 108 176 57 77 21 20 G/C 18 24 18 26 9 23 6 10 C/C 1.00 1.24 d 0.81–1.25 0.80–1.92 0.73–1.20 0.94 0.33–1.54 a 0.60–1.58 0.70–1.32 95% CI 0.72 0.98 0.96 OR G/G versus (G/CþC/C) 1.17 e 1.17 1.17 b 1.34 1.77 0.88 OR 0.81–1.70 0.61–2.26 0.75–1.84 0.45–3.99 0.79–3.98 0.47–1.63 95% CI (G/GþG/C) versus C/C 109 73 130 200 68 53 44 29 G/G 85 94 150 173 74 40 40 35 G/C 30 30 27 38 18 16 9 9 C/C Genotype (counts) 1.04 d 1.61 0.89 a 2.15 0.78 0.77 OR 0.85–1.28 1.09–2.38 0.70–1.12 1.12–4.15 0.48–1.27 0.48–1.27 95% CI 1.14 e 1.16 1.13 b 1.03 1.36 1.06 OR 0.83–1.56 0.67–2.01 0.77–1.66 0.38–2.76 0.66–2.80 0.63–1.77 95% CI G/G versus (G/CþC/C) (G/GþG/C) versus C/C 67 60 67 70 66 67 74 64 G allele frequency (%) 67 64 71 72 67 65 65 67 G allele frequency (%) TABLE III. XBP1116C/G Polymorphism and Schizophrenia in Men: Meta-Analysis of Association Studies w ¼ 0.26, df ¼ 1, NS. Heterogeneity w2 ¼ 0.53, df ¼ 2, NS. w ¼ 0.47, df ¼ 1, NS. Heterogeneity w2 ¼ 1.89, df ¼ 2, NS. c 2 w ¼ 0.01, df ¼ 1, NS. Heterogeneity w2 ¼ 0.58, df ¼ 2, NS. d 2 w ¼ 0.00, df ¼ 1, NS. Heterogeneity w2 ¼ 1.67, df ¼ 3, NS. e 2 w ¼ 0.70, df ¼ 1, NS. Heterogeneity w2 ¼ 1.89, df ¼ 3, NS. f 2 w ¼ 0.17, df ¼ 1, NS. Heterogeneity w2 ¼ 1.28, df ¼ 3, NS. b 2 a 2 Total Chen et al.  Present study, total Present study, Sweden Present study, Poland Present study, Germany References Genotype (counts) TABLE II. XBP1 116C/G Polymorphism and Schizophrenia in Women: Meta-Analysis of Association Studies 0.88–1.22 0.84–1.61 0.82–1.20 0.51–1.59 0.78–1.58 0.75–1.23 95% CI f 1.05 1.34 0.96 c 1.56 0.94 0.87 OR 0.91–1.23 1.01–1.78 0.80–1.15 0.96–2.57 0.65–1.36 0.70–1.09 95% CI G versus C allele 1.03 f 1.17 0.99 c 0.90 1.11 0.96 OR G versus C allele 74 Jönsson et al. DSM-IV or DSM-III-R criteria for schizophrenia, schizoaffective disorder, or schizophreniform disorder, and control subjects from Germany (555 cases, 45% women; 816 controls, 50% women), Poland (273 cases, 41% women; 282 controls, 61% women), and Sweden (122 cases, 39% women; 134 controls, 46% women), respectively. Molecular Genetics Venous blood was drawn from all participants. After DNA isolation, the XBP1 116C/G variant was genotyped as described by Kakiuchi et al. . Genotyping was performed using the MassARRAY system (Sequenom Inc., San Diego, CA) on a modified Bruker Biflex MALDI-TOF mass spectrometer (Sequenom) according to Ding and Cantor  with minor modifications. The resulting mass spectra were analyzed automatically for peak identification using the SpectroTYPER RT 188.8.131.52 software (Sequenom). For quality reasons, two independent persons controlled 10% of the spectra. Individual genotypes were called without the knowledge of phenotypic status. Detailed information of PCR-amplification and genotyping procedure can be obtained by request. Statistics The allele and genotype frequencies among cases and controls were compared using Pearson’s contingency and 2 2 w2-test. Odds ratios (OR), confidence intervals (CI), pooling of data, and testing of heterogeneity between effect sizes were calculated according to Woolf  as previously described [Emery, 1986; Kahn and Sempos, 1989; Jönsson et al., 2004]. RESULTS Genotype distribution in the three different samples is given in Table I. There were no significant deviations from Hardy– Weinberg equilibrium in either patients or controls in any of the samples (data not shown). Neither were there any significant allele (P ¼ 0.23, P ¼ 0.81, and P ¼ 0.25 in the German, Polish, and Swedish sample, respectively), or genotype (P ¼ 0.34, P ¼ 0.19, and P ¼ 0.47, in the German, Polish, and Swedish sample, respectively) differences between cases and controls in either of the samples. Furthermore, there were no significant differences when subjects were analyzed separately according to gender with one exception, that is, in the Swedish sample, schizophrenic men displayed higher G/G frequencies than control men (59% vs. 40%; w2 ¼ 6.02, degree of freedom ¼ 2, P < 0.05). When the three samples were analyzed together, there were no significant association between the G allele, G/G genotype, or C/C genotype, and schizophrenia in the total sample (Table I) or among women (Table II) or men (Table III). When the present samples were analyzed together with previous reported results, there was a significant association between the G-containing genotypes and schizophrenia in the analysis including both genders (Table I). When the original Japanese report was excluded in this metaanalysis, there was no longer evidence for association (w2 ¼ 1.17, odds ratio 1.14, 95% confidence interval 0.90– 1.45). In the remaining meta-analyses no significant differences were detected (Tables I–III). Kakiuchi et al., 2004]. When the data were analyzed, divided with regard to gender, we were not able to detect any significant case-control differences in the total European sample, although in the relatively small Swedish sample there was a higher frequency of the G/G genotype among schizophrenic than control men. When we analyzed all the five different samples comprising 3,612 subjects, there were no significant allele or G/G genotype differences (Table I). However, in the comparison between the GG/GC and CC genotypes there was a borderline association with the G-containing genotypes without evidence for heterogeneity (Table I). This association relied however, to a great extent on the first published study [Kakiuchi et al., 2004], and the meta-analysis was no longer significant when this study was excluded. Although our data do not provide convincing evidence for an association, it cannot be excluded that the XBP1 116C/G variant may confer a small risk to schizophrenia similar to that reported for a functional dopamine D2 receptor variant [Glatt et al., 2003; Jönsson et al., 2003]. It is noteworthy that we observe different odds ratios among Asian and European subjects, which may support an effect in Asian but not Caucasian subjects. A possibly different effect of 116C/G polymorphism in these two populations, however, would be difficult to explain against the notion by Kakiuchi et al.  that this polymorphism is, in itself, a functionally relevant susceptibility variant. To further clarify this topic, additional studies in the Asian and other populations, as well as future meta-analyses are warranted. In conclusion, no firm significant associations were found between the XBP1 116C/G variant and schizophrenia in the present European samples. However, a preliminary metaanalysis of 3,612 subjects suggested an association between the XBP1 functional promoter variant and schizophrenia, and underline the need for further investigations. ACKNOWLEDGMENTS TGS was supported through a Young Investigator Award from the National Alliance for Research on Schizophrenia and Depression (NARSAD). PMC was supported by an Annual Stipend for Young Scientists from the Foundation for Polish Science. We thank Alexandra Tylec, Kjerstin Lind, and Elisabeth Hollsten for technical assistance. REFERENCES Cardno AG, Rijsdijk FV, Sham PC, Murray RM, McGuffin P. 2002. A twin study of genetic relationships between psychotic symptoms. Am J Psychiatry 159:539–545. Chen W, Duan S, Zhou J, Sun Y, Zheng Y, Gu N, Feng G, He L. 2004. A case-control study provides evidence of association for a functional polymorphism 197C/G in XBP1 to schizophrenia and suggests a sex-dependent effect. Biochem Biophys Res Commun 319:866–870. 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