Chromosome 19 locus apolipoprotein C-II association with multiple sclerosis.

We have used a PCR based method to analyze allelic frequencies in a (TG)n(AG)m microsatellite marker located in the first intron of the apolipoprotein C-II gene in French MS patients and controls. Samples were collected from 74 MS patients and from 102 controls. The distribution of microsatellite alleles differed between patients and controls (chi 2 = 7.82), showing a significant effect (P < 0.04) with MS due to the increased frequency of the allele 6 and a decrease frequency (P < 0.03) of allele I. Our study confirms that the apolipoprotein C-II region may influence susceptibility to MS.     

Investigation of a neuronal nitric oxide synthase gene (NOS1) polymorphism in a multiple sclerosis population

Multiple Sclerosis (MS) is a chronic neurological disease characterized by demyelination associated with infiltrating white blood cells in the central nervous system (CNS). Nitric oxide synthases (NOS) are a family of enzymes that control the production of nitric oxide. It is possible that neuronal NOS could be involved in MS pathophysiology and hence the nNOS gene is a potential candidate for involvement in disease susceptibility. The aim of this study was to determine whether allelic variation at the nNOS gene locus is associated with MS in an Australian cohort. DNA samples obtained from a Caucasian Australian population affected with MS and an unaffected control population, matched for gender, age and ethnicity, were genotyped for a microsatellite polymorphism in the promoter region of the nNOS gene. Allele frequencies were compared using chi-squared based statistical analyses with significance tested by Monte Carlo simulation. Allelic analysis of MS cases and controls produced a chi-squared value of 5.63 with simulated P = 0.96 (OR(max) = 1.41, 95% CI: 0.926-2.15). Similarly, a Mann-Whitney U analysis gave a non-significant P-value of 0.377 for allele distribution. No differences in allele frequencies were observed for gender or clinical course subtype (P > 0.05). Statistical analysis indicated that there is no association of this nNOS variant and MS and hence the gene does not appear to play a genetically significant role in disease susceptibility.     

Allelic association of the neuronal nitric oxide synthase (NOS1) gene with schizophrenia

Nitric oxide (NO) has been identified as a widespread and multifunctional biological messenger molecule in the central nervous system (CNS), with possible roles in neurotransmission, neurosecretion, synaptic plasticity, and tissue injury in many neurological disorders, including schizophrenia. Neuronal NO is widely produced in the brain from L-arginine catalyzed by neuronal NO synthase (NOS1). We therefore hypothesized that the NOS1 gene may play a role in the pathophysiology of schizophrenia. In the present study, we examined the genetic association between a novel single nucleotide polymorphism (SNP: a C-->T transition located 276 base pairs downstream from the translation termination site) of the human NOS1 gene, which is located in chromosome 12q24, and schizophrenia (215 Japanese patients with schizophrenia and 182 healthy controls). The allele frequencies of the polymorphism in exon 29 of the NOS1 gene differed significantly between patients with schizophrenia and controls (chi(2) = 20.10, df = 1, P = 0.000007; relative risk = 1.92; 95% confidence interval = 1.44-2.55). Our results suggest that the NOS1 gene polymorphism may confer increased susceptibility to schizophrenia.     

HLA-DRB1基因型与北方汉族多发性硬化易感性的研究

目的 探讨人类白细胞抗原(HLA)-DRB1基因型与中国北方汉族多发性硬化(MS)的关联.方法 应用序列特异性引物-聚合酶链反应(PCR-SSP)技术检测58例中国北方汉族MS患者及63名健康对照者的HLA-DRB1基因型分布;同时将MS患者分为西方型MS和视神经脊髓炎(NMO)两亚组,对其DR4和DR15基因频率进行比较.结果 与对照组比较,MS患者DR15和DR4等位基因频率显著升高(分别为P=0.025,P=0.003);此外,NMO亚组DR4频率显著高于西方型MS(P=0.013).结论 我国北方汉族人MS与HLA-DRB1等位基因的关联与西方人群有所不同,DR15可能是MS的易感基因,而DR4则可能为我国汉族人NMO的易感基因.关联基因的差异可能是导致东西方MS病变部位不同的原因.     

Supportive evidence for an allelic association of the human KCNJ10 potassium channel gene with idiopathic generalized epilepsy

PURPOSE: Quantitative trait loci (QTL) mapping in mice revealed a seizure-related QTL (Szs1), for which the inward-rectifying potassium channel Kcnj10 is the most compelling candidate gene. Association analysis of the human KCNJ10 gene identified a common KCNJ10 missense variation (Arg271Cys) that influences susceptibility to focal and generalized epilepsies. The present replication study tested the initial finding that the KCNJ10 Cys271 allele is associated with seizure resistance to common syndromes of idiopathic generalized epilepsy (IGE). METHODS: The study sample comprised 563 German IGE patients and 660 healthy population controls. To search for seizure type-specific effects, two IGE subgroups were formed, comprising 258 IGE patients with typical absences (IAE group) and 218 patients with juvenile myoclonic epilepsy (JME group). A TaqMan nuclease assay was used to genotype the KCNJ10 single nucleotide polymorphism c.1037C > T (dbSNP: rs1130183) that alters amino acid at position 271 from arginine to cysteine. RESULTS: Replication analysis revealed a significant decrease of the Cys271 allele frequency in 446 IGE patients compared to controls (chi2 = 3.52, d.f. = 1, P = 0.030, one-sided; OR(Cys271+) = 0.69; 95% CI: 0.50-0.95). Among the IGE subgroups, lack of the Cys271 allele was accentuated in the JME group (chi2 = 5.20, d.f. = 1, P = 0.011, one-sided). CONCLUSION: Our results support previous evidence that the common KCNJ10 Arg271Cys missense variation influences seizure susceptibility of common IGE syndromes.     

Preliminary evidences of a NOS2A protective effect from relapsing-remitting multiple sclerosis

The gene encoding the inducible form of Nitric Oxide Synthase (NOS2A) has been considered with interest in the evaluation of the genetic predisposition to Multiple Sclerosis (MS). The aim of the present study was to address the possible contribution of two microsatellites repeats of the NOS2A promoter region - (CCTTT)(n) and (AAAT)(n) - to MS susceptibility. One hundred and thirteen Italian patients with clinically definite RRMS and 237 age and sex matched healthy controls from Calabria (South Italy) were studied. The distribution analysis of the markers frequencies showed that the (CCTTT)(14) allele was found in 11.5% of the RRMS patients and in 25.3% of the healthy subjects, with a statistically significant difference (chi(2)=8.843, p=0.003). This data seems to confer a significant protection against MS (OR=0.348; 95% CI=0.174-0.693, corrected for age and gender). No association with MS susceptibility was observed for the bi-allelic (AAAT)(n) microsatellite. In conclusion, we found that the NOS2A (CCTTT)(14) allele was detected more frequently in the control group than in the RRMS patients, thus confirming the scientific interest on this marker.     

Lack of association of transforming growth factor (TGF)-beta 1 and beta 2 gene polymorphisms with multiple sclerosis (MS) in Northern Ireland.

OBJECTIVE: To examine the influence of TGF-beta genes on MS susceptibility. BACKGROUND: TGF-beta, of which three homologous isoforms exist (1, 2 and 3), is a strongly immunosuppressive cytokine-inhibiting expression of pro-inflammatory cytokines and blocking cytokine induction of adhesion molecules. TGF-beta delays onset of EAE and TGF-beta 1 gene knockout mice develop fatal multifocal inflammatory disease. High TGF-beta levels exist during MS remission whilst E-selectin, whose expression is inhibited by TGF-beta, is found at higher levels in primary progressive disease (PPMS) and it is postulated that the unremitting course of PPMS may be due to low levels of TGF-beta. METHODS: Gene association studies using separate polymorphic microsatellite markers for TGF-beta 1 and TGF-beta 2 were performed, incorporating 151 relapsing-remitting or secondary progressive MS (RR/SPMS) patients, 104 PPMS patients and 159 normal controls (Nor). Forward primers were 5' end-labelled with 6-Fam, PCR products were analysed on an Applied Biosystems 373A fluorescent fragment analyser and Genescan 672 software was used for allele sizing. RESULTS: No significant differences existed in allele frequencies between either MS group and controls regarding the TGF-beta 1 marker: RR/SPMS vs Nor (P = 0.48, df = 8); PPMS vs Nor (P = 0.34, df = 8). Similarly there were no associations demonstrated with the TGF-beta 2 marker: RR/SPMS vs Nor (P = 0.24, df = 2); PPMS vs Nor (P = 0.53, df = 2). CONCLUSION: These data indicate that TGF-beta 1 and beta 2 genes are not loci influencing MS susceptibility, either RR/SPMS or PPMS, in this population.     

Estrogen receptor gene polymorphism and multiple sclerosis in Japanese patients: interaction with HLA-DRB1*1501 and disease modulation

We investigated PvuII and XbaI polymorphism in the estrogen receptor gene (ERG) and HLA-DRB1*1501 positivity in 116 conventional multiple sclerosis (MS) patients and 101 healthy controls in a Japanese population. Logistic analysis revealed independent associations of [P] allele in the profiles for PvuII (p=0.0005, adjusted odds ratio (aOR)=3.17) and DRB1*1501 (p=0.0089, aOR=2.61) with conventional MS. Synergistic elevated risk of MS due to interaction between the [P] allele and HLA-DRB1*1501 allele was found among female patients (odds ratio=16.0; 95% CI=3.99-63.8, p<0.0001). The [P] allele-positive patients with disease duration of more than 5 years had a significantly higher progression index (PI) of disability (p=0.0230) and a worse ranked MS severity score (p=0.0152) than their non-[P] counterparts.     

Tumor necrosis factor-alpha gene polymorphisms in children with multiple sclerosis

Tumor necrosis factor-alpha (TNF-alpha) is a cytokine implicated in the pathogenesis of infectious and autoimmune disorders including multiple sclerosis (MS). Childhood-onset MS presents some clinical and laboratory features differing from adult disease. We studied TNF-alpha - 238 G-->A and - 308 G-->A polymorphisms in 24 patients with childhood-onset MS using PCR-RFLP and compared them with healthy control subjects from the same population (n = 93). The genotypes and allele frequencies were not different between patient and control groups (p = 0.348, 95 %CI, 0.28 - 1.92, chi(2) = 0.10 and p = 0.797, 95 %CI, 0.312 - 2.285, chi(2) = 0.20 for - 238 and - 308 alleles, respectively). Although the size of the study group is small, these results do not support a role for TNF-alpha gene polymorphisms in susceptibility to MS in children.     

Association analysis of the Arg220His variation of the human gene encoding the GABA delta subunit with idiopathic generalized epilepsy

PURPOSE: Mutation analysis of the gene encoding the GABA delta subunit (GABRD) identified a common missense variation (c.659G>A; Arg220His) of which the His220 allele displayed decreased GABA(A) alpha(1)beta(2)delta receptor current amplitudes. The present association study tested whether the functional GABRD His220 allele confers susceptibility to common syndromes of idiopathic generalized epilepsy (IGE). METHODS: Five hundred and sixty two unrelated German IGE patients and 664 healthy population controls were genotyped for the c.659G>A polymorphism in exon 6 of the GABRD gene. RESULTS: His220 allele frequencies did not differ significantly between IGE patients (2.3%) and the controls (2.8%; P=0.46). Likewise, no evidence for an allelic association was found with juvenile myoclonic epilepsy (n=218; 2.8%; P=0.97) or idiopathic absence epilepsy (n=260; 2.3%; P=0.56). CONCLUSION: Our results provide no evidence that the functional GABRD His220 allele mediates a substantial susceptibility effect to common IGE syndromes in the German population.     

Tumor necrosis factor-alpha-308 gene polymorphism in Croatian and Slovenian multiple sclerosis patients

Previous findings regarding the role of TNF-alpha-308 gene polymorphism in multiple sclerosis (MS) are contradictory. The aim of this study was to investigate the possible influence of TNF-alpha-308 polymorphism on MS susceptibility and the MS disease process in a Croatian and Slovenian population. Genotyping was performed in 338 patients and 460 healthy controls. The TNF2 allele was present in 123 (26.8%) healthy controls vs. 67 (19.9%) MS patients (p = 0.023, odds ratio = 0.68, 95% confidence interval = 0.48-0.95), suggesting that carriage of the TNF2 allele might decrease MS risk. The difference in TNF2 allele carrier frequency between patients and controls was identified in the relapsing-remitting MS group. There was no association between TNF2 allele carrier status and age at disease onset or disease progression. Our results suggest that, in the study populations, the TNF-alpha-308 polymorphism may play a role in MS susceptibility.     

2q33区段CD28/ICOS基因多态性与中国南方汉族人群多发性硬化疾病易感性及严重程度关系的研究

目的 探讨2q33区段CD28及ICOS基因多态性与多发性硬化(MS)遗传易感性及病情严重程度的关系.方法 以来自中国南方汉族人群的83名确诊MS患者(MS组)和110名非自身免疫性疾病患者及健康志愿者(对照组)为研究对象,外周静脉血提取DNA,利用PCR-RFLP技术、琼脂糖凝胶电泳技术分析检测扩增产物CD28及ICOS基因的多态性.免疫荧光双标记流式细胞学法检测2组患者外周静脉血淋巴细胞表面CD28及ICOS表达水平.结果 MS组ICOS-2394位点TT基因型频率明显高于对照组(33.7%vs10.9%),T等位基因频率明显高于对照组(56.0%vs30.9%),差异有统计学意义(P＜0.05).3个位点单核苷酸多态性间无明显联合效应.ICOS-2394多态位点TT基因型与原发进展型(PP)-MS发病相关,而CT基因型与继发进展型(SP)-MS发病无关.3个位点基因型及等位基因频率与MS急性期患病严重程度均无明显相关(P＜0.05).MS组外周血淋巴细胞表面CD28及ICOS的表达均明显高于对照组,差异有统计学意义(P＜0.05).结论 中国南方汉族人群ICOS-2394位点多态性与MS发病相关,其中TT基因型与PP-MS发病相关,而CT基因型与SP-MS发病无关,提示该基因为MS的易感基因.CD28基因多态性与MS患病无关.

Abstract：

Objective To investigate the polymorphisms of CD28 and COS genes in chromosome 2q33 region and susceptibility to and severity of multiple sclerosis (MS).Methods Eighty-three patients diagnosed as having MS from Han population of South China were studied; one hundred and ten patients with non-autoimmune diseases or healthy volunteers were selected as controls.DNA was obtained from peripheral venous blood; the polymorphisms of amplified productions (CD28 and ICOS genes) were detected by PCR-RFLP and analyzed by agarose gel electrophoresis.Immunofluorescent two-color flow cytometry was used to study the expressions of CD28 and ICOS genes of lymphocytes in the peripheral blood of these 2 groups. Results The genotype frequency of TT at ICOS-2394 site in patients with MS (33.7%) was significantly higher than that in controls (10.9%,P＜ 0.05), and the allele frequency of T in patient group (56.0%) was obviously higher than that in the controls (30.9%, P＜0.05). No marked combined effects were noted in the 3 SNPs (CD28-372, ICOS-2349 and ICOS-2119). TT genotype in the polymorphic site of ICOS-2394 was correlated to primary progressive MS, while CT genotype in the polymorphic site of ICOS-2394 was not correlated to secondary progressive MS. The genotype and allele frequencies of the 3 SNPs had no marked association with the severity of MS (P＞0.05). The levels of CD28 and ICOS gene expressions in lymphocytes of peripheral blood of patients with MS were significantly higher in patients than that in control group (P ＜ 0.05). Conclusion ICOS polymorphisms might be related to MS in Han population of South China,which suggests that ICOS might be one of genes having susceptibility to MS. No association between CD28 gene polymorphisms and susceptibility to MS is noted.     

Association between variation in the human KCNJ10 potassium ion channel gene and seizure susceptibility

PURPOSE: Our research program uses genetic linkage and association analysis to identify human seizure sensitivity and resistance alleles. Quantitative trait loci mapping in mice led to identification of genetic variation in the potassium ion channel gene Kcnj10, implicating it as a putative seizure susceptibility gene. The purpose of this work was to translate these animal model data to a human genetic association study. METHODS: We used single stranded conformation polymorphism (SSCP) electrophoresis, DNA sequencing and database searching (NCBI) to identify variation in the human KCNJ10 gene. Restriction fragment length polymorphism (RFLP) analysis, SSCP and Pyrosequencing were used to genotype a single nucleotide polymorphism (SNP, dbSNP rs#1130183) in KCNJ10 in epilepsy patients (n = 407) and unrelated controls (n = 284). The epilepsy group was comprised of patients with refractory mesial temporal lobe epilepsy (n = 153), childhood absence (n = 84), juvenile myoclonic (n = 111) and idiopathic generalized epilepsy not otherwise specified (IGE-NOS, n = 59) and all were of European ancestry. RESULTS: SNP rs#1130183 (C > T) alters amino acid 271 (of 379) from an arginine to a cysteine (R271C). The C allele (Arg) is common with conversion to the T allele (Cys) occurring twice as often in controls compared to epilepsy patients. Contingency analysis documented a statistically significant association between seizure resistance and allele frequency, Mantel-Haenszel chi square = 5.65, d.f. = 1, P = 0.017, odds ratio 0.52, 95% CI 0.33-0.82. CONCLUSION: The T allele of SNP rs#1130183 is associated with seizure resistance when common forms of focal and generalized epilepsy are analyzed as a group. These data suggest that this missense variation in KCNJ10 (or a nearby variation) is related to general seizure susceptibility in humans.     

FcRL3 and multiple sclerosis pathogenesis: role in autoimmunity?

BACKGROUND AND AIMS: A functional promoter polymorphism in the FcRL3 gene, -169 T/C, has been shown to regulate gene expression and to play a role in several autoimmune diseases. We aimed at testing for the first time whether this gene was involved in multiple sclerosis (MS) pathogenesis. METHODS: Case-control study performed with 400 Spanish MS patients and 508 healthy subjects. Genotyping of -169 T/C and -110 G/A was ascertained by using TaqMan MGB chemistry following manufacturer suggestions (Applied Biosystems, CA, USA). RESULTS: As previously seen for other autoimmune diseases, a significant difference was observed in the distribution of -169 T/C FcRL3 genotypes between MS patients and healthy controls (p = 0.03; chi(2) = 6.99). The -169 T allele, recently associated with increased susceptibility to Addison's disease, showed a parallel effect in MS [(TT+TC) vs. CC: p = 0.013; OR = 1.55 (1.08-2.54)]. CONCLUSIONS: An increased susceptibility associated to the -169 T allele was found when MS patients and controls were compared, supporting the role of the FcRL3 locus in MS predisposition and therefore extending the evidence of its general influence on autoimmunity.     

ITGA4 polymorphisms and susceptibility to multiple sclerosis

In multiple sclerosis (MS), alpha(4)beta(1) integrin, also known as Very Late Antigen 4 (VLA4), facilitates migration of leukocytes across the blood brain barrier. Several studies suggest that expression of alpha(4) integrin may be increased in MS patients compared to controls, and down-regulation or antagonism of alpha(4) integrin may be associated with immunomodulatory treatment success. We analysed association of 13 single nucleotide polymorphisms (SNPs) in the gene encoding alpha(4) integrin (ITGA4) with susceptibility to MS in two distinct populations comprising cases and controls from the Basque Country in northern Spain (352 patients; 235 controls) and Nordic countries (1119 patients; 1235 controls). Carriage of the C allele of the ITGA4 promoter SNP rs1449263 was independently and weakly increased in MS patients from each population compared to respective controls (P = 0.037 in Basque; and P = 0.042 in Nordic cohorts), though these associations were lost upon application of permutation correction. Meta-analysis of rs1449263*C carriage revealed a Mantel-Haenszel common OR of 1.26 (95% CI 1.06-1.49; P = 0.0069). Though our data only modestly argue for a role of ITGA4 in determining susceptibility to MS, we suggest that further examination of this gene, particularly the promoter region, is warranted.     

Genetic analysis of tumor necrosis factor-alpha (TNF-alpha) G-308A and Saitohin Q7R polymorphisms with Alzheimer's disease

Neuroinflammation and abnormal phosphorylation of TAU proteins have been implicated in the etiology of Alzheimer's disease (AD). Several studies have suggested the G-308A promoter polymorphism in one of the proinflammatory cytokine genes tumor necrosis factor-alpha (TNF-alpha) encoding TNF-alpha may be associated with AD pathogenesis. Association between the Q7R polymorphism in saitohin (STH), a gene nested within the intron of the Tau gene, has also been reported. To determine whether these two polymorphisms contribute to the risk for late-onset AD (LOAD) in Chinese, we have investigated 207 sporadic LOAD patients and 222 healthy controls. The associations of the AA genotype and A-allele with LOAD (chi(2) = 8.74, df = 1, P = 0.0031, and chi(2) = 4.47, df = 1, P = 0.035) were found. After stratifying by apolipoprotein E allele 4 (APOE epsilon4) status, increased LOAD risks associated with the AA genotype and A-allele only in the APOE epsilon4 non-carriers (chi(2) = 9.21, df = 1, P = 0.002; chi(2) = 10.02, df = 1, P = 0.0015) were seen. These results suggested that the TNF-alpha gene G-308A polymorphism might be a risk factor for LOAD and dependent on APOE epsilon4 status in Chinese. Homozygous Q/Q of STH Q7R polymorphism was the only one genotype found in either LOAD group or controls. No R allele was detected in LOAD and control groups. The extremely rare frequency of the ancestral R allele differs sharply from that observed in studies in the Caucasian population, suggesting obvious ethnic differences.     

Pilot association study of the beta-glucocerebrosidase N370S allele and Parkinson's disease in subjects of Jewish ethnicity.

Mutations in the beta-glucocerebrosidase gene cause Gaucher's disease, one of the most common lysosomal lipid storage diseases in the Ashkenazi Jewish population. The occurrence of parkinsonism in patients with Type 1 Gaucher's disease has been noted previously. In this pilot study, we evaluated a possible association between Parkinson's disease (PD) and the beta-glucocerebrosidase gene N370S allele (nt.1226 A>G) in 160 Parkinson's disease patients and 92 controls of Jewish ethnicity. We observed a higher frequency of the N370S genotype in PD cases (NS and SS, 10.7%) compared to controls (NS and SS 4.3%); however, the difference was not statistically significant (chi(2) = 3.4, P = 0.2). A total of 17 PD cases carry the N370S allele, including 2 homozygotes and 15 heterozygotes. The N370S allele (nt.1226 A>G) may be associated with PD in patients of Jewish ethnicity and should be examined in a larger study.     

Evidence that variation at the serotonin transporter gene influences susceptibility to attention deficit hyperactivity disorder (ADHD): analysis and pooled analysis

Reduced central serotonergic activity has been implicated in poor impulse regulation and aggressive behaviour in animals, adults and also young children.(1,2) Two recently published studies have implicated variation at a polymorphism in the promoter of the serotonin transporter (5HTT; hSERT) in influencing susceptibility to ADHD.(3,4) Consistent with these results we have also found a trend for the long allele of the promoter polymorphism to influence susceptibility to ADHD in a sample of 113 ADHD parent proband trios (65 transmissions vs 49 non-transmissions, chi(2) = 2.25, P = 0.13). A pooled analysis of our, and these published results demonstrated a significant over representation of the long allele of the promoter in ADHD probands compared to controls (chi(2) = 7.14, P = 0.008). We have also examined two other 5HTT polymorphisms (the VNTR in intron 2 and the 3' UTR SNP). TDT analysis demonstrated preferential transmission of the T allele of the 3' UTR SNP (chi(2) = 4.06, P = 0.04). In addition, ETDT analysis of haplotypes demonstrated significant preferential transmission of haplotypes containing the T allele of the 3' UTR SNP with the long allele of the promoter polymorphism (chi(2) = 13.18, 3 df, P = 0.004) and the 10 repeat of the VNTR (chi(2) = 8.77, 3 df, P = 0.03). This study provides further evidence for the possible involvement of the serotonin transporter in susceptibility to ADHD.     

Genetic association analysis of neuronal nitric oxide synthase gene polymorphism with tardive dyskinesia

Possible involvement of oxidative stress in the pathophysiology of tardive dyskinesia (TD) has been proposed. Long-term administration of neuroleptics alters dopaminergic turnover, yielding the increase of the formation of reactive oxygen species (ROS), which may lead to TD through neuronal toxicity as a consequence of oxidative stress. In the present study, the relationship between TD and a polymorphism of the neuronal nitric oxide synthase (NOS1) gene whose reaction product, nitric oxide (NO), is involved in oxidative stress was studied in 171 Japanese patients with schizophrenia, including 41 patients meeting TD criteria. The C/T polymorphism in exon 29 of the NOS1 gene was genotyped using polymerase chain reaction (PCR) amplification followed by restriction enzyme digestion. No significant difference in genotype frequencies was detected between subjects with and without TD (chi2 = 1.54, df = 2, p = 0.46). In addition, there was no difference in allele frequencies (chi2 = 0.42, df = 1, p = 0.51). These results suggest that the NOS1 gene polymorphism may not confer increased susceptibility to TD, although more investigations on other populations are warranted.     

Mutation screening and LD mapping in the VCFS deleted region of chromosome 22q11 in schizophrenia using a novel DNA pooling approach

We examined whether variation within six genes from the VCFS critical region at 22q11 (DGSC, Stk22A1, DGSI, Gscl, Slc25A1 and Znf74) confers susceptibility to schizophrenia. We screened the exons and flanking intronic sequence of each gene for mutations in 14 individuals with DSM-IV schizophrenia using DHPLC. All polymorphisms identified were characterised and genotyped in a sample of 184 schizophrenics and matched controls, using novel DNA pooling methods. Of the polymorphisms identified, 17 were located within exons, six were within coding sequence, and two were non-synonymous. Pooled genotyping revealed no differences in the allele frequencies for any polymorphism between cases and controls that met our pre-defined criterion (P < or = 0.1). In a complementary approach we also attempted to define the location of a schizophrenia susceptibility locus more precisely by performing association mapping using seven microsatellites spanning the VCFS region with an average inter-marker distance of 450 kb. Conventional chi(2) analysis of genotypes in 368 cases and 368 controls revealed that none of the markers was significantly associated (P < 0.05) with schizophrenia. However, evidence for significant association (P = 0.003) was obtained for D22S944 when alleles were combined. TDT analysis of D22S944 genotyped in a further 278 cases of schizophrenia and their parents failed to find any overall allele-wise significant transmission disequilibrium (chi(2) = 18.3, P = 0.17). However, individual analysis of the alleles revealed that allele 12 was excessively non-transmitted and that this almost reached significance when corrected for multiple alleles (chi(2) = 7.35, P = 0.006, P = 0.078 corrected for 13 alleles).