基于核心家系的EGR3基因与精神分裂症的关联研究

研究表明位于染色体8p21.3区域的EGR3(Early growth response 3)是精神分裂症(Schizophrenia)的重要易感基因,然而,仍有两个病例-对照研究未能验证上述发现。为了研究EGR3基因在我国患者中是否与疾病关联,文章在中国汉族的核心家系中选择EGR3基因座位上的5个SNPs位点(rs1996147、rs1877670、rs3750192、rs35201266和rs7009708)进行基因分型和传递不平衡检验(Transmission disequilibrium test,TDT)。结果表明遗传标记rs1996147和rs3750192分别显示出显著的传递不平衡(2>4.40,P<0.05)。在连锁不平衡分析中,由2个(rs3750192和rs35201266)、3个(rs1877670、rs3750192和rs7009708)以及4个(rs1996147、rs1877670、rs3750192和rs7009708)SNPs位点构建的单倍型均显示与精神分裂症显著性关联(2>7.10,整体P<0.05)。总之,EGR3基因与中国汉族人群精神分裂症遗传易感性相关,后续关于EGR3基因进一步的功能研究将会更好的帮助我们了解该基因在疾病病理学机制中的作用。     

基于核心家系的EGR3基因与精神分裂症的关联研究

研究表明位于染色体8p21.3区域的EGR3(Early growth response 3)是精神分裂症(Schizophrenia)的重要易感基因, 然而, 仍有两个病例-对照研究未能验证上述发现。为了研究EGR3基因在我国患者中是否与疾病关联, 文章在中国汉族的核心家系中选择EGR3基因座位上的5个SNPs位点(rs1996147、rs1877670、rs3750192、rs35201266和rs7009708)进行基因分型和传递不平衡检验(Transmission disequilibrium test, TDT)。结果表明遗传标记rs1996147和rs3750192分别显示出显著的传递不平衡(c²>4.40, P<0.05)。在连锁不平衡分析中, 由2个(rs3750192和rs35201266)、3个(rs1877670、rs3750192和rs7009708)以及4个(rs1996147、rs1877670、rs3750192和rs7009708)SNPs位点构建的单倍型均显示与精神分裂症显著性关联(c²>7.10, 整体P<0.05)。总之, EGR3基因与中国汉族人群精神分裂症遗传易感性相关, 后续关于EGR3基因进一步的功能研究将会更好的帮助我们了解该基因在疾病病理学机制中的作用。     

Social Cognitive Role of Schizophrenia Candidate Gene GABRB2

The occurrence of positive selection in schizophrenia-associated GABRB2 suggests a broader impact of the gene product on population fitness. The present study considered the possibility of cognition-related GABRB2 involvement by examining the association of GABRB2 with psychosis and altruism, respectively representing psychiatric and psychological facets of social cognition. Four single nucleotide polymorphisms (SNPs) were genotyped for quantitative trait analyses and population-based association studies. Psychosis was measured by either the Positive and Negative Syndrome Scale (PANSS) or antipsychotics dosage, and altruism was based on a self-report altruism scale. The minor alleles of SNPs rs6556547, rs1816071 and rs187269 in GABRB2 were correlated with high PANSS score for positive symptoms in a Han Chinese schizophrenic cohort, whereas those of rs1816071 and rs1816072 were associated with high antipsychotics dosage in a US Caucasian schizophrenic cohort. Moreover, strongly significant GABRB2-disease associations were found among schizophrenics with severe psychosis based on high PANSS positive score, but no significant association was observed for schizophrenics with only mild psychosis. Interestingly, in addition to association with psychosis in schizophrenics, rs187269 was also associated with altruism in healthy Han Chinese. Furthermore, parallel to correlation with severe psychosis, its minor allele was correlated with high altruism scores. These findings revealed that GABRB2 is associated with psychosis, the core symptom and an endophenotype of schizophrenia. Importantly, the association was found across the breadth of the psychiatric (psychosis) to psychological (altruism) spectrum of social cognition suggesting GABRB2 involvement in human cognition.     

Association of the carboxyl-terminal PDZ ligand of neuronal nitric oxide synthase gene with schizophrenia in the Chinese Han population

Several independent linkage studies have demonstrated that the 1q22 region is likely to harbor candidate schizophrenia susceptibility genes. Recently, some genetic variants within CAPON have been reported as exhibiting significant linkage disequilibrium to schizophrenia in Canadian familial-schizophrenia pedigrees. We examined nine single nucleotide polymorphisms (SNPs), which span an approximately 236-kb region of CAPON, in 664 schizophrenia cases and 941 controls in the Chinese Han population. We detected a significant difference in allele distributions of SNP rs348624 (P = 0.000017). Moreover, the overall frequency of haplotypes constructed from three SNPs including rs348624 showed significant difference between cases and controls (P = 0.000025). Our findings indicate that CAPON gene may be a candidate susceptibility gene for schizophrenia in Chinese Han population, and also provide further support for the potential importance of NMDAR-mediated glutamatergic transmission in the etiology of schizophrenia.     

GABRB2 Haplotype Association with Heroin Dependence in Chinese Population

Substance dependence is a frequently observed comorbid disorder in schizophrenia, but little is known about genetic factors possibly shared between the two psychotic disorders. GABRB2, a schizophrenia candidate gene coding for GABA_A receptor β₂ subunit, is examined for possible association with heroin dependence in Han Chinese population. Four single nucleotide polymorphisms (SNPs) in GABRB2, namely rs6556547 (S1), rs1816071 (S3), rs18016072 (S5), and rs187269 (S29), previously associated with schizophrenia, were examined for their association with heroin dependence. Two additional SNPs, rs10051667 (S31) and rs967771 (S32), previously associated with alcohol dependence and bipolar disorder respectively, were also analyzed. The six SNPs were genotyped by direct sequencing of PCR amplicons of target regions for 564 heroin dependent individuals and 498 controls of Han Chinese origin. Interestingly, it was found that recombination between the haplotypes of all-derived-allele (H1; OR = 1.00) and all-ancestral-allele (H2; OR = 0.74) at S5-S29 junction generated two recombinants H3 (OR = 8.51) and H4 (OR = 5.58), both conferring high susceptibility to heroin dependence. Additional recombination between H2 and H3 haplotypes at S1-S3 junction resulted in a risk-conferring haplotype H5 (OR = 1.94x10⁹). In contrast, recombination between H1 and H2 haplotypes at S3-S5 junction rescued the risk-conferring effect of recombination at S5-S29 junction, giving rise to the protective haplotype H6 (OR = 0.68). Risk-conferring effects of S1-S3 and S5-S29 crossovers and protective effects of S3-S5 crossover were seen in both pure heroin dependent and multiple substance dependence subgroups. In conclusion, significant association was found with haplotypes of the S1-S29 segment in GABRB2 for heroin dependence in Han Chinese population. Local recombination was an important determining factor for switching haplotypes between risk-conferring and protective statuses. The present study provide evidence for the schizophrenia candidate gene GABRB2 to play a role in heroin dependence, but replication of these findings is required.     

Family-based association study of synapsin II and schizophrenia

Synapsin II has been proposed as a candidate gene for vulnerability to schizophrenia on the basis of its function and its location in a region of the genome implicated by linkage studies in families with schizophrenia. We recently reported positive association of synapsin II with schizophrenia in a case-control study (Chen et al. 2004). However, since case-control analyses can generate false-positive results in the presence of minor degrees of population stratification, we have performed a replication study in 366 additional Han Chinese probands and their parents by use of analyses of transmission/disequilibrium for three in/del markers and three single-nucleotide polymorphisms. Positive association was observed for rs2307981 (P =.02), rs2308169 (P =.005), rs308963 (P =.002), rs795009 (P =.02), and rs2307973 (P =.02). For transmission of six-marker haplotypes, the global P value was.0000016 (5 degrees of freedom), principally because of overtransmission of the most common haplotype, CAA/-/G/T/C/- (frequency 53.6%; chi (2) = 20.8; P =.0000051). This confirms our previous study and provides further support for the role of synapsin II variants in susceptibility to schizophrenia.     

A genetic study of two calcium-independent cytosolic PLA2 genes in schizophrenia

The present study detected 9 single nucleotide polymorphisms (SNPs) at the PLA2G4C and PLA2G6 loci among 240 Chinese parent-offspring trios of Han descent. Of these 9 SNPs, 5 showed highly polymorphic in the Chinese population. They were then applied as genetic markers to test the genetic association of these two calcium-independent cytosolic PLA2 genes with schizophrenia. The transmission disequilibrium test (TDT) showed that rs1549637 at the PLA2G4C locus was the only SNP associated with the illness (chi(2) = 5.63, P = 0.018). The global P-value was 0.082 for 1000 permutations with the TDT analysis. Neither the conditional on allele test nor the conditional on genotype test showed a disease association for the combination of these two genes. Because the PLA2G4C association is so weak, this initial finding should be interpreted with caution.     

Association of G72/G30 with schizophrenia in the Chinese population

Recently, the G72 gene was reported to be associated with schizophrenia in the French Canadian and Russian populations. Here, we report the results obtained from the study of six single-nucleotide polymorphisms (SNPs: rs3916965, rs3916967, rs2391191, rs1935062, rs778293, and rs3918342), which span an 82-kb region covering the complementary DNA sequences of G72 and G30, in 537 schizophrenia cases and 538 controls of the Han Chinese. In this work, we have identified statistically significant differences in allele distributions of two markers rs3916965 (P = 0.019) and rs2391191 (P = 0.0010), and a highly significant association between haplotype AGAC of the G72/G30 locus (P = 1.7 x 10(-4)) and schizophrenia. Our data provide further evidence that markers of the G72/G30 genes are associated with schizophrenia in a non-Caucasian population.     

A family based study of the genetic association between the PLA2G4D gene and schizophrenia

The present study detected two single nucleotide polymorphisms (SNPs) at the PLA2G4D locus, rs2459692 and rs4924618, to investigate a genetic association between the PLA2G4D gene and schizophrenia. A total of 236 Chinese parent-offspring trios of Han descent were recruited for the genetic analysis. The transmission disequilibrium test (TDT) did not show allelic association either for rs2459692 (chi(2) = 0.217, P = 0.641) or for rs4924618 (chi(2) = 0.663, P = 0.416). To see the combined effect of the PLA2G4D locus with the other three PLA2G4 genes, we applied the above two SNPs as a conditional marker to test the pair-wise combination for a disease association. The conditioning on allele (COA) test revealed a weak association for the rs2459692-PLA2G4A combination (chi(2) = 6.03, df = 2, P = 0.049), the rs2459692-PLA2G4B combination (chi(2) = 7.16, df = 3, P = 0.028) and the rs4924618-PLA2G4C combination (chi(2) = 7.01, df = 2, P = 0.03), whereas the conditioning on genotype (COG) test showed a weak association only for the rs4924618-PLA2G4C combination (chi(2) = 8.52, df = 3, P = 0.036). Because we performed a multi-locus analysis in this study, the weak association shown by the conditional tests could make little biological sense. In conclusion, the PLA2G4D gene may not be involved in a susceptibility to schizophrenia.     

Polymorphisms in the glutamate decarboxylase 1 gene associated with heroin dependence

The GAD1 gene encodes the 67-kDa glutamic acid decarboxylase isoform (GAD67), the rate-limiting enzyme responsible for γ-aminobutyric acid (GABA) biosynthesis from glutamic acid, and may be involved in the development of drug dependence. To identify markers contributing to the genetic susceptibility to heroin dependence, this study examined the potential association between heroin dependence and 15 single nucleotide polymorphisms (SNPs, rs1978340, rs3762556, rs3791878, rs3749034, rs11542313, rs2241165, rs2241164, rs769407, rs3749033, rs16858977, rs701492, rs16858988, rs4668331, rs7578661, rs769395) of GAD1 gene using the MassARRAY system. Participants included 370 heroin-dependent subjects and 389 healthy controls. The allelic or genotypic frequencies of the rs1978340 (promoter region), rs3791878 (promoter region), and rs11542313 (exon 3) polymorphisms in heroin addicts were significantly different from those in healthy controls. Strong linkage disequilibrium was observed in two blocks (D'>0.9). Significantly more C-C-C-C-A haplotypes (p=0.0053 after Bonferroni correction) and significantly fewer T-C-A-C-A haplotypes (p=0.0003 after Bonferroni correction) were found in heroin dependent subjects. These findings point to a role for GAD1 polymorphism in heroin dependence among Han Chinese, and may be informative for future genetic or neurobiological studies on heroin dependence.     

Association between promoter variants of interleukin-18 and schizophrenia in a Han Chinese population

An increasing amount of evidence suggests that interleukin-18 (IL-18) plays a pivotal role in the pathophysiology of schizophrenia. However, association between single nucleotide polymorphism of IL-18 and the risk of schizophrenia has not been clarified. This study examined whether two promoter polymorphisms -137 G/C (rs187238) and -607 C/A (rs1946518) of IL-18 were associated with schizophrenia and six clinical symptoms (disorder of perception, thought disorder, disturbance of emotion, disorder of behavior and volition, suicide action, and aggressive action) to provide data for screening high-risk Han Chinese individuals. Three hundred seventy-two schizophrenic patients and 353 healthy controls from a Han Chinese population were examined to assess their genotype and allele frequencies of the two promoter polymorphisms of IL-18. The genotype distributions in both patients and controls were within Hardy-Weinberg equilibrium. No significant differences were observed in the genotype or the allele frequencies of the two single-nucleotide polymorphisms between patients and controls. However, genotype frequencies of -607 C/A showed significant differences between patients and controls in the appearance of perception disorder (χ2 = 6.153, p = 0.046). A significant difference was detected in -137 G/C between patients and controls in the appearance of aggressive action (χ2 = 3.909, p = 0.048). In conclusion, IL-18 gene promoter polymorphisms may not contribute to the susceptibility of schizophrenia in a Han Chinese population, but two single-nucleotide polymorphisms, -137 G/C and -607 C/A, may play a role in the development of perception disorder and aggressive action, respectively.     

Abnormal changes of plasma acute phase proteins in schizophrenia and the relation between schizophrenia and haptoglobin (Hp) gene

Summary. In this study we focused on detecting schizophrenia related changes of plasma proteins using proteomic technology and examining the relation between schizophrenia and haptoglobin (Hp) genotype. We investigated plasma proteins from schizophrenic subjects (n = 42) and healthy controls (n = 46) by two-dimensional gel electrophoresis (2-DE) in combination with mass spectrometry. To further reveal the genetic relationship between acute phase proteins (APPs) and schizophrenia disease, we tested Hp α1/Hp α2 (Hp 1/2) polymorphism and two single nucleotide polymorphisms (SNPs) of Hp, rs2070937 and rs5473, for associations with schizophrenia in the Chinese Han population. With the relatively high number of samples for 2-DE work, we found that four proteins in the family of positive APPs were all up-regulated in patients. In genetic association study, we found significant associations existing between schizophrenia and Hp polymorphisms, Hp 1/2 and rs2070937 variants. Schizophrenia is accompanied by both an altered expression of Hp protein and a different genotype distribution of Hp gene, demonstrating that Hp is associated with schizophrenia. The results from proteomic and genomic aspects both indicate that acute phase reaction is likely to be an aetiological agent in the pathophysiology of schizophrenia, but not just an accompanying symptom. The positive APPs are schizophrenic related proteins, with the highly concordant results on four positive APPs. The first two authors contributed equally.     

Association analysis of the RGS4 gene in Han Chinese and Scottish populations with schizophrenia

We investigated the RGS4 as a susceptibility gene for schizophrenia in Chinese Han (184 trios and 138 sibling pairs, a total of 322 families) and Scottish (580 cases and 620 controls) populations using both a family trio and case-control design. Both the samples had statistical power greater than 70% to detect a heterozygote genotype relative risk of >1.2 for frequent RGS4-risk alleles. We genotyped four single nucleotide polymorphisms (SNPs) which have previously been associated with schizophrenia as either individually or part of haplotypes. Allele frequencies and linkage disequilibrium between the SNPs was similar in the two populations. In the Chinese sample, no individual SNPs or any of their haplotypes were associated with schizophrenia. In the Scottish population, one SNP (SNP7) was significantly over-represented in the cases compared with the controls (0.44 vs. 0.38; A allele; chi(2) 7.08, P = 0.011 after correction for correlation between markers by permutation testing). One two-marker haplotype, composed of alleles T and A of SNP4 and SNP7, respectively, showed individual significance after correction by permutation testing (chi(2) 6.8; P = 0.04). None of the full four-marker haplotypes showed association, including the G-G-G-G haplotype previously associated with schizophrenia in more than one sample and the A-T-A-A haplotype. Thus, our data do not directly replicate previous associations of RGS4, but association with SNP 7 in the Scottish population provides some support for a role in schizophrenia susceptibility. We cannot conclusively exclude RGS4, as associated haplotypes are likely to be surrogates for unknown causative alleles, whose relationship with overlying haplotypes may differ between the population groups. Differences in the association seen across the two populations could result from methodological factors such as diagnostic differences but most likely result from ethnic differences in haplotype structures within RGS4.     

Identification of significant association and gene-gene interaction of GABA receptor subunit genes in autism

Autism is a common neurodevelopmental disorder with a significant genetic component. Existing research suggests that multiple genes contribute to autism and that epigenetic effects or gene-gene interactions are likely contributors to autism risk. However, these effects have not yet been identified. Gamma-aminobutyric acid (GABA), the primary inhibitory neurotransmitter in the adult brain, has been implicated in autism etiology. Fourteen known autosomal GABA receptor subunit genes were studied to look for the genes associated with autism and their possible interactions. Single-nucleotide polymorphisms (SNPs) were screened in the following genes: GABRG1, GABRA2, GABRA4, and GABRB1 on chromosome 4p12; GABRB2, GABRA6, GABRA1, GABRG2, and GABRP on 5q34-q35.1; GABRR1 and GABRR2 on 6q15; and GABRA5, GABRB3, and GABRG3 on 15q12. Intronic and/or silent mutation SNPs within each gene were analyzed in 470 white families with autism. Initially, SNPs were used in a family-based study for allelic association analysis--with the pedigree disequilibrium test and the family-based association test--and for genotypic and haplotypic association analysis--with the genotype-pedigree disequilibrium test (geno-PDT), the association in the presence of linkage (APL) test, and the haplotype family-based association test. Next, with the use of five refined independent marker sets, extended multifactor-dimensionality reduction (EMDR) analysis was employed to identify the models with locus joint effects, and interaction was further verified by conditional logistic regression. Significant allelic association was found for markers RS1912960 (in GABRA4; P = .01) and HCV9866022 (in GABRR2; P = .04). The geno-PDT found significant genotypic association for HCV8262334 (in GABRA2), RS1912960 and RS2280073 (in GABRA4), and RS2617503 and RS12187676 (in GABRB2). Consistent with the allelic and genotypic association results, EMDR confirmed the main effect at RS1912960 (in GABRA4). EMDR also identified a significant two-locus gene-gene effect model involving RS1912960 in GABRA4 and RS2351299 in GABRB1. Further support for this two-locus model came from both the multilocus geno-PDT and the APL test, which indicated a common genotype and haplotype combination positively associated with disease. Finally, these results were also consistent with the results from the conditional logistic regression, which confirmed the interaction between GABRA4 and GABRB1 (odds ratio = 2.9 for interaction term; P = .002). Through the convergence of all analyses, we conclude that GABRA4 is involved in the etiology of autism and potentially increases autism risk through interaction with GABRB1. These results support the hypothesis that GABA receptor subunit genes are involved in autism, most likely via complex gene-gene interactions.     

Association of TNFAIP3 polymorphism with rheumatic heart disease in Chinese Han population

In a pair-matched case–control study (239 versus 478) conducted in Chinese Han population, we investigated the association between tumor necrosis factor-α-induced protein 3 (TNFAIP3) gene, tumor necrosis factor receptor-associated factor 1 (TRAF1) gene, complement component 5 (C5) gene, and rheumatic heart disease (RHD). We observed no association with RHD for the five tagging single nucleotide polymorphisms (tSNP) in the C5 gene, the three tSNPs in the TNFAIP3 gene, or the two tSNPs in the TRAF1 gene. However, we determined that the tSNP, rs582757, located at intron_5 of the TNFAIP3 gene, associated with RHD in Chinese Han population. Both the distribution of genotype and allele frequencies differed significantly between case and control subjects (p?=?0.001 and p?=?0.0004, respectively). The minor C allele reduced the risk of RHD with a per-allele odds ratio of 0.57 (0.42–0.78) for the additive model in univariate analysis (p?=?0.000). Under a dominant model, CC/CT carriers had a 0.54-fold reduced risk of RHD (95% confidence interval 0.38–0.75, p?=?0.000) than TT carriers. Therefore, we report a new genetic variant (rs582757) in the TNFAIP3 gene that associated with the prevalence of RHD in Chinese Han population. Further genetic and functional studies are required to identify the etiological variants in linkage disequilibrium with this polymorphism.     

Interpopulation linkage disequilibrium patterns of GABRA2 and GABRG1 genes at the GABA cluster locus on human chromosome 4

GABRA2 and GABRG1, which encode the alpha-2 and gamma-1 subunits, respectively, of the GABA(A) receptor, are located in a cluster on chromosome 4p. The GABRA2 locus has been found to be associated with alcohol dependence in several studies, but no functional variant that can account for this association has been identified. To understand the reported associations, we sought to understand the linkage disequilibrium (LD) patterns and haplotype structures of these genes. With close intergenic distance, approximately 90 kb, it was anticipated that some markers might show intergenic LD. Variation in 13-SNP haplotype block structure was observed in five different populations: European American, African American, Chinese (Han and Thai), Thai, and Hmong. In the Hmong, a 280-kb region of considerably higher LD spans the intergenic region, whereas in other populations, there were two or more LD blocks that cross this region. These findings may aid in understanding the genetic association of this locus with alcohol dependence in several populations.     

A further study of a possible locus for schizophrenia on the X chromosome

Several studies suggest that the X chromosome may contain a gene for schizophrenia. In the present study, we recruited 142 male schizophrenic patients and their biological mothers from all parts of the United Kingdom to detect a genetic association for the SYP/CACNA1F locus in the Xp11 region and the FACL4 locus in the Xq22.3-Xq23 region. The haplotype-based haplotype relative risk (HHRR) analysis showed allelic association for rs2071316 (chi2=6.85, P=0.009) and rs5905724 (chi2=5.3, P=0.021) at the CACNA1F locus, but not for rs5943414 and rs1324805 at the FACL4 locus and rs3817678 at the SYP locus. The haplotype analysis showed a weak association for the rs3817678-rs2071316-rs5905724 haplotypes (chi2=12.19, df=4, P=0.016) but did not show such an association for the rs5943414-rs1324805 haplotypes (chi2=3.96, df=2, P=0.138). Because the linkage disequilibrium signal was detected only at the CACNA1F locus, this gene should perhaps be considered as being a candidate for schizophrenia although further work is needed to draw firm conclusions.     

延边朝鲜族和汉族脂联素启动子SNPs与原发性高血压的相关性

为了探讨延边朝鲜族和汉族脂联素基因启动子单核苷酸多态性(SNPs)与原发性高血压(EH)的关系, 文章采用PCR产物直接测序方法检测了220例EH患者和268例对照个体的脂联素启动子5个SNPs位点: -11426A>G(rs16861194)、-11391G>A(rs17300539)、-11377C>G(rs62620185)、-11156insCA(rs60806105)、-11043C>T(rs76786086), 氧化酶法测定空腹血糖、甘油三酯、总胆固醇、低密度脂蛋白、高密度脂蛋白, 酶联免疫吸附法(ELISA)测定血浆脂联素和胰岛素。结果显示: (1) -11426A>G、-11377C>G 和-11156insCA 3个位点具有多态性, 且它们的基因型频率分布符合Hardy-Weinberg平衡定律(P>0.05), -11391G>A和-11043C>T位点无多态性; (2) -11426A>G和-11156insCA呈完全连锁不平衡(D’=1; r2=1); (3) -11426G基因频率比较, 朝鲜族(21.10%)高于汉族(12.05%), 汉族EH组高于对照组; -11377C>G的基因型和基因频率在朝鲜族和汉族间及同一民族内EH组和对照组间比较均无统计学意义(P>0.05); (4)单倍型?11426G -11377C的频率, 汉族EH组高于对照组(P<0.05), 朝鲜族EH组和对照组比较无统计学意义(P>0.05); (5)EH组的血浆脂联素水平明显低于对照组(P<0.001)。据此得出结论: (1)首次发现?11426A>G和?11156insCA呈完全连锁不平衡, -11426 A>G的多态性在朝鲜族和汉族中存在民族差异; (2) -11426 G和-11426G -11377C是延边汉族EH的危险因子和危险单倍型, 但不是朝鲜族的; (3)低血浆脂联素是延边朝鲜族和汉族EH的重要危险因素; (4)血浆脂联素水平与-11426A>G基因型无关。     

Linkage analysis of plasma dopamine ��-hydroxylase activity in families of patients with schizophrenia

Dopamine β-hydroxylase (DβH) catalyzes the conversion of dopamine to norepinephrine. DβH enters the plasma after vesicular release from sympathetic neurons and the adrenal medulla. Plasma DβH activity (pDβH) varies widely among individuals, and genetic inheritance regulates that variation. Linkage studies suggested strong linkage of pDβH to ABO on 9q34, and positive evidence for linkage to the complement fixation locus on 19p13.2-13.3. Subsequent association studies strongly supported DBH, which maps adjacent to ABO, as the locus regulating a large proportion of the heritable variation in pDβH. Prior studies have suggested that variation in pDβH, or genetic variants at DβH, associate with differences in expression of psychotic symptoms in patients with schizophrenia and other idiopathic or drug-induced brain disorders, suggesting that DBH might be a genetic modifier of psychotic symptoms. As a first step toward investigating that hypothesis, we performed linkage analysis on pDβH in patients with schizophrenia and their relatives. The results strongly confirm linkage of markers at DBH to pDβH under several models (maximum multipoint LOD score, 6.33), but find no evidence to support linkage anywhere on chromosome 19. Accounting for the contributions to the linkage signal of three SNPs at DBH, rs1611115, rs1611122, and rs6271 reduced but did not eliminate the linkage peak, whereas accounting for all SNPs near DBH eliminated the signal entirely. Analysis of markers genome-wide uncovered positive evidence for linkage between markers at chromosome 20p12 (multi-point LOD?=?3.1 at 27.2?cM). The present results provide the first direct evidence for linkage between DBH and pDβH, suggest that rs1611115, rs1611122, rs6271 and additional unidentified variants at or near DBH contribute to the genetic regulation of pDβH, and suggest that a locus near 20p12 also influences pDβH.     

Meta-Analysis Indicates That the European GWAS-Identified Risk SNP rs1344706 within ZNF804A Is Not Associated with Schizophrenia in Han Chinese Population

Recent genetic association studies have implicated several candidate susceptibility variants for schizophrenia among general populations. Rs1344706, an intronic SNP within ZNF804A, was identified as one of the most compelling candidate risk SNPs for schizophrenia in Europeans through genome-wide association studies (GWASs) and replications as well as large-scale meta-analyses. However, in Han Chinese, the results for rs1344706 are inconsistent, and whether rs1344706 is an authentic risk SNP for schizophrenia in Han Chinese is inconclusive. Here, we conducted a systematic meta-analysis of rs1344706 with schizophrenia in Chinese population by combining all available case-control samples (N = 12), including a total of 8,982 cases and 12,342 controls. The results of our meta-analysis were not able to confirm an association of rs1344706 A-allele with schizophrenia (p = 0.10, odds ratio = 1.06, 95% confidence interval = 0.99–1.13). Such absence of association was further confirmed by the non-superiority test (p = 0.0003), suggesting that rs1344706 is not a risk SNP for schizophrenia in Han Chinese. Detailed examinations of individual samples revealed potential sampling bias in previous replication studies in Han Chinese. The absence of rs1344706 association in Han Chinese suggest a potential genetic heterogeneity in the susceptibility of schizophrenia on this locus and also demonstrate the difficulties in replicating genome-wide association findings of schizophrenia across different ethnic populations.