Synapsin III gene polymorphisms and schizophrenia

Synapsins are synaptic vesicle-associated phosphoproteins and are thought to play crucial roles in synaptogenesis and neurotransmitter release. Synaptic abnormalities have been reported in the pathophysiology of schizophrenia. In addition, the synapsin III gene, a member of the synapsin gene family, has been located at 22q12-13, which has been suggested as a potential susceptibility locus for schizophrenia. We investigated a genetic association between schizophrenia and the synapsin III gene polymorphisms (-631C/G and -196G/A) in 160 schizophrenic patients and 153 controls. No significant positive association between either polymorphism and schizophrenia was observed. Furthermore, no significant association was observed between either polymorphism and the diagnostic subtypes. Our results suggested that the synapsin III gene polymorphisms do not confer increased susceptibility to schizophrenia.     

Systematic mutation analysis of the human glutamate receptor,ionotropic, N-methyl-D-aspartate 1 gene(GRIN1) in schizophrenic patients

Schizophrenia is a severe, complex mental disorder with unknown etiology. Abnormal glutamate neurotransmission has been proposed as one of the hypotheses of the pathogenesis of schizophrenia. Mohn recently reported that transgenic mice with the reduced glutamate receptor, ionotropic, -methyl-D-aspartate 1 gene (GRIN1) (formerly referred to as NMDAR1) expression display schizophrenia-like behaviors, which can be ameliorated by antipsychotic drug treatment. Their report promoted us to examine whether mutations in the human GRIN1 gene may convey genetic susceptibility to schizophrenia. To test this possibility, we systematically screened mutations in the promoter region and in all the exons of the human GRIN1 gene in a cohort of Chinese schizophrenic patients from Taiwan. Using single-strand conformation polymorphism analysis and autosequencing, we identified two single nucleotide polymorphisms, designated g.-1140G>A and g.-855G>C, respectively, at the 5'-untranslated region of the human GRIN1 gene. Genetic association study, however, revealed no association of these two single nucleotide polymorphisms with schizophrenia in our patients. Besides, no other mutations of the human GRIN1 gene were detected in this study. Our data suggest that the human GRIN1 gene may not contribute substantially to the genetic etiology of schizophrenia in our population.     

Association of schizophrenia in African Americans to polymorphism in synapsin III gene

Linkage studies in families with schizophrenia have pointed to chromosome 22q12-q13 as one of several regions of the genome that may contain a susceptibility gene. The gene coding for synapsin III, an intrinsic synaptic vesicle membrane protein, maps to this target region. Two tightly linked single-nucleotide polymorphisms were recently found in a small subset of patients with SZ - a synonymous variant, L469L (469G>A), and a non-synonymous variant, S470N (470G>A) - which results in the loss of a mitogen-activated protein kinase serine phosphorylation site. We also found a slight increase in 470A in Caucasian patients from the US with schizophrenia. But, the sample size and allele frequency were too small to draw definitive conclusions. However, both single-nucleotide polymorphisms were much more polymorphic in African American controls than in Caucasian controls, thereby providing a better sample cohort to analyze for schizophrenia involvement. For the codon 469 single-nucleotide polymorphisms, a 50-fold increase was observed in the frequency of 469A in African Americans compared with Caucasians. Furthermore, there was an increase in the percentage of African American patients with schizophrenia who were homozygous for the 469A allele compared with controls who were homozygous (11 versus 5%; AA vs. all other genotypes - Fisher statistic=3.08, P=0.04, one-tailed). An increase in 470A heterozygotes was also found, but the results fell short of being statistically significant. The findings support a role for synapsin III in a subset of African American patients with schizophrenia and raises questions about selective pressure in Africa to account for the extraordinary disparity of the 469 and 470 single-nucleotide polymorphisms in different ethnic populations.     

Linkage and family-based association study of schizophrenia and the synapsin III locus that maps to chromosome 22q13

The human synapsin III gene (synapsin III) is a member of a neuron-specific phosphoprotein gene family involved in short-term neurotransmitter release. We mapped synapsin III to chromosomal region 22q13 (13.1-13.31) by fluorescence in situ hybridization, a region that has been identified as a potential schizophrenia susceptibility locus. The dinucleotide repeat marker D22S280 located in intron 5 of synapsin III was genotyped in a linkage and family-based association study to assess the role of the synapsin III locus in the etiology of schizophrenia. In 12 pedigrees with periodic catatonia comprising 135 individuals, we found exclusion of linkage of marker D22S280 using lod score analysis with autosomal dominant/recessive models as well as affected only LOD score methods with dominant/recessive models. In a family-based association study of 61 unrelated parent-offspring trios with schizophrenia (according to the the Diagnostic and Statistical Manual of Mental Disorders, fourth edition [DSM-IV, American Psychiatric Association, 1994]), we found no association of individual D22S280 alleles to disease. Results of a multiallelic transmission/disequilibrium test (TDT(max) = 3.00; P = 0.55) challenged the possibility that D22S280 alleles appear with DSM-IV schizophrenia more frequently than expected. In addition, no evidence for gender differences or parent-of-origin effects were found. Thus, the synapsin III locus at chromosome 22q13 is not likely to contain a schizophrenia susceptibility gene.     

Identification of novel single nucleotide substitutions in the NKp30 gene expressed in human natural killer cells

Cytotoxicity of natural killer (NK) cells is regulated by a balance of signals from two kinds of NK receptors, activating receptors and inhibitory receptors. Natural cytotoxicity receptors (NCR) family, which consists of NKp30, NKp44 and NKp46, is a major human activating NK receptor. NKp30 has been mapped to the HLA class III region near tumor necrosis factor (TNF) family loci. We have analyzed the NKp30 gene of healthy Japanese and found two synonymous substitutions in the coding region, c.111G>A and c.156C>T, and also identified two single-nucleotide polymorphisms (SNPs) in the promotor region, -201G>A and -163G>C. Furthermore, it was confirmed that these polymorphisms of the NKp30 gene show strong linkage disequilibria with each other and with HLA-DRB1 or TNFA polymorphisms. Since susceptibilities to certain diseases were mapped near this region, the NKp30 polymorphisms could be useful genetic markers.     

Identification of four novel polymorphisms in the calcitonin/alpha-CGRP (CALCA) gene and an investigation of their possible associations with Parkinson disease, schizophrenia, and manic depression

We identified novel polymorphisms in the calcitonin/CGRPalpha (CALCA) gene by direct sequencing of genomic DNA and subsequent genotyping by RFLP (restriction fragment length polymorphism) detection and investigated association with neurological or psychiatric disease. Four novel polymorphic alleles were found: two (g.979G>A and g.4218T>C) represented single nucleotide polymorphisms (SNPs), one consisted of two coupled SNPs in close vicinity to each other (g.1210T>C and g.1214C>G), and one was an intronic 16-bp microdeletion (2919-2934del16). One of the SNPs (g.4218T>C) causes a non-synonymous amino acid change (Leu66Pro) in the third exon, an exon common to both procalcitonin and pro-alpha-CGRP. In a subsequent association study, frequencies of the identified polymorphisms in Parkinson and schizophrenia patients were compared with frequencies in the normal population. No statistically significant association was found in our material. The 16-bp microdeletion polymorphism was present in a family with multiple cases of unipolar or bipolar depressive disorder. Using this polymorphism as marker, cosegregation with the phenotype was observed in the majority of individuals.     

Mutation analysis of the N-methyl-D-aspartate receptor NR1 subunit gene (GRIN1) in schizophrenia

Dysfunction of N-methyl-D-aspartate (NMDA) type ionotropic glutamate receptors has been implicated in the etiology of schizophrenia based on psychotomimetic properties of the antagonist phencyclidine (PCP) and observation that mice expressing low levels of the N-methyl-D-aspartate receptor NR1 subunit exhibit behavioral alterations that may be ameliorated by neuroleptic drugs. Based on the hypothesis that some schizophrenic patients have functionally deficient mutation(s) of the gene encoding N-methyl-D-aspartate receptor NR1 subunit (GRIN1), we screened 48 Japanese patients with schizophrenia for mutations in the coding region of the GRIN1 gene. Four variants, IVS2-22T>C, IVS2-12G>A, IVS4-34C>T, and 1719G/A (Pro516Pro), were identified. No non-synonymous mutation was detected. No significant association was suggested by case-control comparisons. Results indicate that genomic variations of the GRIN1 gene are not likely to be involved substantially in the etiology of schizophrenia.     

A functional polymorphism in the promoter region of the dopamine D2 receptor gene is associated with schizophrenia

An excess dopaminergic activity may be implicated in the etiology of schizophrenia. Our objective was to identify nucleotide variants in the 5' region of the dopamine D2 receptor gene (DRD2) and to clarify their effects on schizophrenia. We identified two polymorphisms, the A-241G and -141C Ins/Del, by examination of 259 bp in the 5'-flanking region and 249 bp of exon 1 of DRD2. Reporter constructs containing the -141C Del allele cloned into a luciferase reporter plasmid drove 21% (Y-79 cells) and 43% (293 cells) expression compared with the -141C Ins allele. In a case-control study, the -141C Del allele frequency was significantly lower in 260 schizophrenic patients than in 312 controls (OR = 0.60, 95%CI 0.44-0.81, P < 0.001). No significant association was found between the A-241G polymorphism and in vitro luciferase activity, or in allele frequency between the patients versus controls. These findings show that the -141C Ins/Del may be a functional polymorphism in the 5'-promoter region of DRD2 and may affect the susceptibility to schizophrenia.      

CCM2 gene polymorphisms in Italian sporadic patients with cerebral cavernous malformation: a case-control study

Cerebral cavernous malformations (CCMs) are vascular lesions of the CNS characterized by abnormally enlarged capillary cavities that can occur sporadically or as a familial autosomal dominant condition with incomplete penetrance and variable clinical expression attributable to mutations in three different genes: CCM1 (Krit1), CCM2 (MGC4607) and CCM3 (PDCD10). Among our group of CCM Italian patients, we selected a cohort of sporadic cases negative for mutations in CCM genes. In this cohort, five variants in CCM2 gene were detected, which proved to be the known polymorphisms in intronic regions (IVS2-36A>G and IVS8 +119 C>T) and in coding sequence (c.157 G>A in exon 2, c.358 G>A in exon 4 and c.915 G>A in exon 8). Therefore, we undertook a case-control study to investigate the possible association of these polymorphisms with sporadic CCMs. The five polymorphisms were identified in 91 CCM sporadic patients and in 100 healthy controls by direct sequencing methods using lymphocyte DNA. Polymorphisms IVS2-36A>G and c.915 G>A showed statistically significant differences in frequencies between patients and controls [(χ2, 6.583; P<0.037); (χ2, 14.205; P<0.001)]. The prevalence of the wild-type genotype was significantly lower in the CCM group than in the control sample. Patients with the A/G and G/G genotypes (IVS2-36A>G) had a significant increase for CCM risk (OR, 3.08; 95% CI, 1.5-5.9 and OR, 4.3; 95% CI, 1.4-22.6) and the same was observed for the polymorphism c.915 G> A (genotype G/A OR, 6.1; 95% CI, 3.0-12.6 and genotype A/A OR, 2.79). In addition, the polymorphisms c.358 G>A in exon 4 (χ2, 15.977; P<0.04) and c.915 G>A in exon 8 (χ2, 18.109; P<0.02) were significantly associated with different types of symptoms. Haplotype analysis, performed only on polymorphisms c.358 G>A (p.Val120Ile), c.915 G>A (p.Thr305 Thr) and IVS2-36A>G, shows that haplotype GAG (+--) significantly increased among CCM sporadic patients compared to the control group. Significant differences between patients and controls were observed only for IVS2-36A>G and c.915 G>A polymorphisms indicating their possible association with sporadic CCMs and an increased risk of CCM. On the other hand, polymorphisms c.358 G>A and c.915 G>A were associated with a more benign course of the disease. These data were confirmed by the haplotype GAG (+--) frequencies.     

DNA methylation and mRNA expression of <Emphasis Type="Italic">SYN III</Emphasis>, a candidate gene for schizophrenia

Background  

The synapsin III (SYN III) gene on chromosome 22q is a candidate gene for schizophrenia susceptibility due to its chromosome location, neurological function, expression patterns and functional polymorphisms.     

Human p53 tumor suppressor gene (TP53) and schizophrenia: case-control and family studies

The human p53 tumor suppressor gene (TP53) is considered as a candidate susceptibility gene for schizophrenia because of its functions in neurodevelopment. To test for an association between TP53 and schizophrenia, both the case-control study and the transmission disequilibrium test (TDT) were performed on genotype data from eight polymorphisms in TP53. Our samples included 286 Toronto schizophrenia cases and 264 controls, and 163 Portuguese nuclear families. In the Toronto case-control study significant differences of allele frequencies of the CAA Ins/Del (p=0.027) and the 16bp Ins/Del (p=0.022) were detected. In TDT analysis we found significant differences for transmission of the CAA Ins/Del (p=0.017) in Portuguese schizophrenia families. Haplotype analysis also showed a significant association between TP53 and schizophrenia. These results provide further evidence that TP53 may play a role in the pathogenesis of schizophrenia.     

Association study of IL2/IL21 and FcgRIIa: significant association with the IL2/IL21 region in Scandinavian coeliac disease families

The first genome-wide association study performed in a UK coeliac disease (CD) case-control cohort revealed association with a linkage disequilibrium block containing the KIAA1109/Tenr/IL2/IL21 genes. Also recently, an association with a non-synonymous polymorphism in FcgammaRIIa (CD32a) was reported in CD with an unusually strong P-value. We aimed to replicate the reported associations with the single nucleotide polymorphisms rs13119723 A>G and rs6822844 G>T in the KIAA1109/Tenr/IL2/IL21 region and rs1801274 G>A in the FcgammaRIIa gene in a family sample consisting of 325 Swedish/Norwegian families using the robust transmission disequilibrium test. The family sample used in this study included 100 families with two or more children affected by CD and 225 families with one affected child. We could confirm significant association between the polymorphisms rs13119723 A>G and rs6822844 G>T located in the KIAA1109/Tenr/IL2/IL21 region and CD (P-value 0.001 and 0.002, respectively). However, we found no association with the FcgammaRIIa rs1801274 G>A polymorphism (P-value=0.3). In conclusion, our results support the KIAA1109/Tenr/IL2/IL21 region as a true CD susceptibility region.     

Mutations in exons 2 and 3 of the FOLR1 gene in demented and non-demented elderly subjects

We have previously reported six novel mutations in the 5'-UTR of the gene for folate receptor-alpha (FOLR1). In our search for additional mutations we screened patients, referred for investigation of suspected dementia (DGM subgroup) by SSCP and DNA sequencing from the end of exon 1 to the first bases of intron 3. We found 4 sequence variations, FOLR1 g.1314G>A, g.1816delC, g.1841G>A, and g.1928C>T. Pyrosequencing genotyping assays were developed for all of them, and 389 active seniors (AS subgroup) and the 202 DGM patients were genotyped for these mutations. The frequency q of the mutated allele was, among the AS subjects, 0.068, 0.0026, 0.0026, and 0.024 respectively, and among the DGM subjects, 0.067, 0.0076, 0.0078, and 0.023. The g.1816delC and g.1841G>A mutations thus were more frequent in the DGM than in the AS subgroup, but the difference did not reach statistical significance. The mutated alleles, FOLR1 1816(-) and 1841A, always occurred together in the same subjects, suggestive of a rare double-mutant haplotype. The two common polymorphisms, FOLR1 g. 1314G>A and g.1928C>T seemed not to raise tHcy plasma levels, whereas the double-mutated g.1816(-)-g.1841A haplotype may possibly have a slight tHcy-raising effect. Thus, so far 8 novel rare FOLR1 mutations with a combined prevalence of approximately 1.3% in Whites as well as two common polymorphisms with 5% and 13%, respectively, have been demonstrated. Only a few of the rare mutations may potentially be associated with raised plasma tHcy concentrations. No association with dementia was found.     

Functional FEN1 polymorphisms are associated with DNA damage levels and lung cancer risk

Flap endonuclease 1 (FEN1) is a key enzyme in maintaining genomic stability and protecting against carcinogenesis. This study investigated whether functional variations in FEN1 gene are associated with DNA damage and lung cancer risk. Thirty DNA samples were sequenced to identify variants and function of the variants was examined by a set of biochemical assays. DNA damage levels were detected by comet assays in a cohort of 303 coke‐oven workers and 297 controls. The association with lung cancer risk was examined in two independent case–control panels consisted of a total 1,840 lung cancer patients and 1,958 controls. We identified two single nucleotide polymorphisms (SNPs) located in the FEN1 promoter c.?69G>A (rs174538:G>A) and 3′‐untranslational region c.4150G>T (rs4246215:G>T) that were associated with reduced FEN1 expression. Among coke‐oven workers, DNA damage levels were significantly higher in the ?69GG or GA carriers compared with the ?69AA carriers. The ?69GG or 4150GG carriers had a significantly increased risk for developing lung cancer compared with the ?69AA or 4150TT carriers. These results highlight FEN1 as an important gene in human carcinogenesis and genetic polymorphisms in FEN1 confer susceptibility to lung cancer. Hum Mutat 30:1–9, 2009. © 2009 Wiley‐Liss, Inc.     

单胺氧化酶A基因多态性与精神分裂症的关联研究

目的探讨河南地区汉族人群单胺氧化酶A（monoamine oxidase A，MAOA）基因多态性与精神分裂症的关系。方法参照CCMD-3诊断标准，选取212例精神分裂症患者与168名正常对照，应用聚合酶链反应及限制性片段长度多态性技术检测MAOA基因多态性，采用病例一对照的关联分析方法对精神分裂症患者及正常对照的基因型和等位基因频率进行分析。结果（1）MAOA基因的基因型在患者组和对照组中均符合Hardy-Weinberg平衡定律（X^2=0．618，dr：2，P〉0、05；X^2=3．173，df=2，P〉0．05）。（2）MAOA基因的基因型和等位基因频率在患者组与对照组间的分布差异无统计学意义（P〉0．05）。（3）按性别分组，男性患者组中CT基因型分布频率显著高于男性对照组（X^2=7．654，P=0．022）。（4）MAOA基因的基因型和等位基因频率在家族史阴、阳性间的分布差异无统计学意义（P〉0．05）。结论没有发现MAOA基因多态性与汉族精神分裂症的发病有关联，但对性别发病有影响，基因型CT可能是男性精神分裂症发病的易感因素。     

New founder germline mutations of CDKN2A in melanoma-prone families and multiple primary melanoma development in a patient receiving levodopa treatment

Germline mutations in the CDKN2A gene have been shown to predispose individuals to cutaneous malignant melanoma. Here, we describe three melanoma-prone families and one isolated patient affected by multiple melanoma who carried a tandem germline mutation of CDKN2A at the nucleotide level, [c.339G>C;c.340C>T], [p.Leu113Leu;p.Pro114Ser]. We also describe three other melanoma-prone families that carried a missense germline CDKN2A mutation, c.167G>T, p.Ser56Ile. All these families and patients resided in southeast France. We analyzed six 9p21 markers where the CDKN2A gene is located and found that carrier haplotypes for both mutations were consistent with two respective common founder ancestors. In one family, we identified two fourth-degree relatives homozygous for the Ser56Ile mutation, indicating a possible consanguinity. Furthermore, we observed that a carrier of the founder CDKN2A [p.Leu113Leu;p.Pro114Ser] mutation as well as two MC1R moderate-risk variants, [p.Arg151Cys(+)p.Arg163Gln] developed 22 primary melanomas in the three years that followed initiation of levodopa therapy for Parkinson's disease. This observation suggests that there is a need for reconsideration of the hypothesis that levodopa may play a role in melanoma development, at least when in the context of a high-risk genetic background.     

Association of polymorphisms in the haplotype block spanning the alternatively spliced exons of the NTNG1 gene at 1p13.3 with schizophrenia in Japanese populations

Chromosome 1p13 is linked with schizophrenia in Japanese families, and one of the candidate genes in this region is the netrin G1 (NTNG1) gene at 1p13.3. Associations of 56 tag single-nucleotide polymorphisms (SNPs) with schizophrenia were explored by transmission disequilibrium analysis in 160 Japanese trios and by case-control analysis in 2,174 Japanese cases and 2,054 Japanese controls. An association between SNP rs628117 and schizophrenia was identified by case-control comparison (nominal allelic p=0.0009; corrected p=0.006). The associated polymorphism is located in intron 9 and in the haplotype block encompassing the alternatively spliced exons of the gene. Allelic association of a different SNP in the same haplotype block in Japanese families was previously reported. These findings support that the NTNG1 gene is associated with schizophrenia in the Japanese.