人类葡萄糖-6-磷酸脱氢酶的分子生物学研究进展

葡萄糖-6-磷酸脱氢酶(glucose-6-phosphate dehydrogenase,G6PD)缺乏症作为一种全球范围内最常见的酶缺乏症之一,受到研究者们的广泛关注.G6PD催化磷酸戊糖途径的第一步,由此酶催化生成的NADPH+H+对于对抗氧化性损伤是极其重要的.本文将从G6PD的结构与功能,SNP的研究与单体型的建立,抗疟疾选择优势与新的G6PD基因突变检测方法这几方面的研究进展综述如下.     

血管紧张素原基因与黎族原发性高血压并脑梗死相关性

目的 研究血管紧张素原（AGT）基因四个位点的单核苷酸多态及其构成的单倍型与海南黎族原发性高血压并脑梗死的相关性.方法 选择海南黎族人群为研究对象,利用PCR-直接测序法,在100例原发性高血压并脑梗死患者和100例健康对照者中,对AGT基因启动子区域的G-152A,A-20C,C-18T,A-6G多态进行基因分型.结果原发性高血压并脑梗死组与健康对照组相比,C-18T多态的基因型和等位基因频率分布差异均有显著性（P=0.002,P=0.002）.A-6G多态的G等位基因频率在原发性高血压并脑梗死组显著高于对照组（P=0.016）.单倍型分析提示由-20C和-6G构成的H6单倍型在原发性高血压并脑梗死组中明显增加,与对照组相比有显著性差异（P=0.003）.结论 在海南黎族人群中,A-20C,C-18T,A-6G多态可能是原发性高血压并脑梗死发病的遗传危险因素.     

Association of polymorphism of tumor necrosis factor-alpha gene promoter region with outcome of hepatitis B virus infection

AIM: To determine whether -238G/A and -857C/T polymorphisms of tumor necrosis factor-alpha (TNF-α), gene promoter and hepatitis B (HB) viral genotypes were associated with outcomes of HBV infection. METHODS: A total of 244 HBV self-limited infected subjects, 208 asymptomatic carriers, and 443 chronic HB patients were recruited to conduct a case-control study. TNF-a -238G/A and -857C/T gene promoter polymorphisms were examined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), and HBV genotypes were examined by nested PCR. RESULTS: The positive rate of HBV DNA in asymptomatic carrier group and chronic HB group was 46.6% and 49.9%, respectively. HBV genotype proportion among the asymptomatic carriers was 2.1% for genotype A, 25.8% for genotype B, 68.0% for genotype C, and 4.1% for genotype B+C mixed infection, and 0.9% for genotype A, 21.7% for genotype B, 71.5% for genotype C, 5.9% for genotype B+C mixed infection in chronic HB group. There was no significant difference in genotype distribution between the asymptomatic carrier group and chronic HB group (X2 = 1.66, P = 0.647). The frequency of -238GG genotype in self-limited group was 95.1%, significantly higher than 90.7% in chronic HB group and 89.0% in asymptomatic carrier group (P= 0.041 and P= 0.016, respectively).The frequency of TNF-α-857 CC in chronic HB group was 79.7%, significantly higher than 64.4% in asymptomatic carrier group and 70.9% in self-limited group (P<0.001 and P= 0.023, respectively). A multiple logistic regression analysis revealed that TNF-α-238GA and -857CC were independently associated with chronic HB after gender and age were adjusted. CONCLUSION: TNF-α promoter variants are likely to play a substantial role in the outcome of HBV infection.     

A novel 3-bp deletion in the PANK2 gene of Dutch patients with pantothenate kinase-associated neurodegeneration: evidence for a founder effect

Mutation analysis was performed in four apparently unrelated Dutch families with pantothenate kinase-associated neurodegeneration, formerly known as Hallervorden-Spatz syndrome. A novel 3-bp deletion encompassing the nucleotides GAG at positions 1,142 to 1,144 of exon 5 of the PANK2 gene was found in all patients. One patient was compound heterozygous; she also carried a novel nonsense mutation (Ser68Stop). The other patients were homozygous for the 1142_1144delGAG mutation. The 1142_1144delGAG mutation was also found in a German patient of unknown descent. We used polymorphic microsatellite markers flanking the PANK2 gene (spanning a region of approximately 8 cM) for haplotype analyses in all these families. A conserved haplotype of 1.5 cM was found for the 1142_1144delGAG mutation carriers. All the Dutch families originated from the same geographical region within the Netherlands. The results indicate a founder effect and suggest that the 1142_1144delGAG mutation probably originated from one common ancestor. It was estimated that this mutation arose at the beginning of the ninth century, approximately 38 generations ago.     

Single nucleotide polymorphisms and haplotypes of histamine <Emphasis Type="Italic">N</Emphasis>-methyltransferase in patients with gastric ulcer

Introduction: Histamine plays a crucial role in the regulation of gastric acid secretion, which is involved in the pathogenesis of peptic ulcer. Histamine N-methyltransferase (HNMT) is the major metabolizing enzyme for histamine inactivation in human stomach.Objective: This study aims to determine whether there exists a relationship between HNMT gene polymorphisms and the risk for gastric ulcer (GU).Methods: 118 GU patients and 154 ethnically matched control subjects were enrolled and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assays were developed to genotype all these subjects for the T-1637C, C-411T, C314T and A1097T point mutations in HNMT gene. Haplotypes were reconstructed from the genotype data.Results: Frequencies of the variant alleles in cases and controls were 0.398 vs 0.396 for T-1637C, 0.144 vs 0.110 for C-411T, 0.034 vs 0.042 for C314T, and 0.242 vs 0.273 for A1097T, respectively, with no significant difference for any locus between the two groups (all P > 0.05). Also the frequencies of genotypes, haplotypes and haplotype pairs based on these polymorphisms did not differ significantly between cases and controls.Conclusion: This study provided no evidence for the involvement of HNMT polymorphisms in the susceptibility to GU.Received 5 February 2004; returned for revision 10 March 2004; accepted by A. Falus 22 April 2004     

Comprehensive association analysis of APOE regulatory region polymorphisms in Alzheimer disease

Several recent case-control studies have examined the association between single nucleotide polymorphisms (SNPs) in the promoter region of the apolipoprotein E gene (APOE) and risk of Alzheimer disease (AD), with conflicting results. We assessed the relation between five APOE region SNPs and risk of AD in both case-control and family-based analyses. We observed a statistically significant association with the +5361T allele in the overall case-control analysis (P value=0.04) after adjusting for the known effect of the APOE-4 allele. Further analysis revealed this association to be limited to carriers of the APOE-4 allele. Age-stratified analyses in the patients with age at onset of 80 years or greater and age-matched controls showed that the –219T allele (P value=0.009) and the +113C allele (P value=0.03) are associated with increased risk of AD. Despite these findings, haplotype and family-based association analyses were unable to provide evidence that the APOE region SNPs influenced risk of AD independent of the APOE-4 allele. In addition to risk, we tested for association between the SNPs and age at onset of AD, but found no association in the case-control or family based analyses. In conclusion, SNPs +5361, or a SNP in strong linkage disequilibrium, may confer some additional risk for developing AD beyond the risk due to APOE-4; however, the effect independent of APOE-4 is likely to be small.     

β-Adrenoceptor polymorphisms

There can be no doubt that ₁-, ₂- and ₃-adrenoceptor genes have genetic polymorphisms. Two single nucleotide polymorphisms have been described for the ₁- (Ser49Gly; Gly389Arg), three for the ₂- (Arg16Gly; Gln27Glu; Thr164Ile) and one for the ₃-adrenoceptor subtype (Trp64Arg) that might be of functional importance. The possibility that changes in expression or properties of the -adrenoceptors due to single nucleotide polymorphisms might have phenotypic consequences influencing their cardiovascular or metabolic function or may contribute to the pathophysiology of several disorders like hypertension, congestive heart failure, asthma or obesity is an idea that has attracted much interest during the last 10 years. At present, it appears that these -adrenoceptor polymorphisms are very likely not disease-causing genes, but might be risk factors, might modify disease and/or might influence progression of disease. The aim of this review is to provide an overview of the functional consequences of such -adrenoceptor polymorphisms in vitro, ex vivo and in vivo.     

Differential expression of human COMT alleles in brain and lymphoblasts detected by RT-coupled 5′ nuclease assay

Rationale A common polymorphism, Val158Met, alters catechol-O-methyltransferase (COMT) enzyme activity and has been linked to psychiatric phenotypes. Bray et al. (2003) reported that COMT is subject to differential allele expression in brain, finding modest (13–22%) underexpression of a haplotype containing Val158. However, disparate findings by another group who used the same method, but in lymphoblasts, raise the issues of tissue specificity, magnitude of differential expression, and identity of loci altering expression.Objectives We measured COMT allele expression ratios in heterozygous human lymphoblast cell lines and brains.Methods Using transcribed single nucleotide polymorphisms as endogenous reporters, we developed an RT-coupled 5 nuclease assay for allele expression ratios and applied it to 63 COMT rs4818(C>G) heterozygotes and 68 Val158Met [rs4680(G>A)] heterozygotes.Results For rs4818(C>G), the C allele was overexpressed relative to the G allele in 18 of 27 lymphoblast lines and 23 of 36 brains. For Val158Met, Met158 was overexpressed relative to Val158 in all (29 of 29) lymphoblast lines and all (39 of 39) brains. Each of the 22 rs4818 heterozygotes without differential allele expression was a Val158/Val158 homozygote. The Met158 allele was overexpressed by 65–77% when compared with Val158 in lymphoblasts and brain. Haplotype augmented ability to predict expression in brain only. However, the expression of the Val158 allele on the high-expressing haplotype was only 19% higher than Val158 alleles on the other haplotype background.Conclusions COMT alleles are differentially expressed. The Met158 allele predicts higher mRNA expression in both brain and lymphoblasts. As exemplified here, the RT-coupled 5 nuclease assay is a reliable method for the quantitative evaluation of cis-acting regulatory effects.     

Spanish population data and forensic usefulness of a novel Y-STR set (DYS437, DYS438, DYS439, DYS460, DYS461, GATA A10, GATA C4, GATA H4)

DNA typing of 8 recently described STRs on the Y chromosome was carried out by means of 2 multiplex amplification reactions for 134 unrelated males from Cantabria, a region in northern Spain. Multiplex 1 included loci DYS460 (GATA A7.1), GATA A10, GATA H4 and DYS439; multiplex 2 included DYS461 (GATA A7.2), GATA C4, DYS437 and DYS438. Haplotype diversity was found to be 99.36%, similar to that obtained with the standard 9-STR set ("minimal haplotype") of the European Y-user group (99.35%). The 13-locus haplotype resulting from the combination of the standard minimal haplotype and the 4-locus multiplex 1 showed a 99.89% diversity. Further inclusion of the 4 loci in multiplex 2 resulted in a haplotype diversity of 99.93%. The combination of the "minimal haplotype" and the multiplex 1 in the present study may be an efficient way of increasing the power of discrimination in forensic cases.     

Detection of the four sequence variations of MDR1 gene using TaqMan MGB probe based real-time PCR and haplotype analysis in healthy Japanese subjects

OBJECTIVES: P-glycoprotein (P-gp) is significant from the viewpoint of pharmacokinetics/pharmacodynamics (PK/PD). MDR1 gene encodes P-gp and has a wide variety of SNPs. As the SNPs may be one of the factors that induce pharmacogenetic individual difference, haplotype analysis is necessary to evaluate the PK/PD. DESIGN AND METHODS: The SNPs of the detected MDR1 were -129T>C, 325G>A, 2677G>T/A, and 3435C>T. For the analysis of linkage disequilibrium (LD) and haplotype analysis, and for the reconstruction of the haplotype pair, ARLEQUIN and PHASE were employed. RESULTS: The result of the chi(2) test detected significant LD between -129 and 2677, -129 and 3435, and 2677 and 3435. There were 9 haplotypes: T-G-C, T-T-C, C-T-C, T-A-C, C-A-C, T-G-T, T-T-T, C-G-T, and C-T-T. CONCLUSIONS: LD was found among the positions -129, 2677 and 3435. As a result, 9 haplotypes exists in the Japanese population. These results suggest that it would be necessary to give consideration to haplotype for the purpose of evaluating the PK/PD of the drugs transported by P-gp.