Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Single nucleotide polymorphisms (SNPs)”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5Linked to original sources
PubMed2006

Single nucleotide polymorphisms (SNPs) at CDH1 promoter region in familial gastric cancer.

INTRODUCTION: Gastric cancer is the most frequent gastrointestinal malignancy in Mexico and the proportion of patients younger than 40 years is one of the highest reported in the world literature. Recently several families with familial diffuse gastric cancer have been identified at the National Institute of Medical Sciences and Nutrition. Germline mutations in the E-cadherin gene (CHD1) have been described that result in the development of diffuse hereditary gastric cancer in young patients. METHODS: The complete coding sequence at exons 1 to 16 and the promoter region of CDH1 was amplified by polymerase chain reaction in peripheral blood samples of two patients with early onset familial diffuse gastric cancer. RESULTS: No germline inactivating mutations of CHD1 were found on either patient. Single nucleotide polymorphisms -160 C->A were detected in the promoter region of CDH1 in both patients. CONCLUSIONS: The polymorphism -160 C->A theoretically confers an increased risk of developing diffuse gastric cancer. The relatives of these patients may an increased risk of gastric cancer among other tumors. There is presently not enough evidence to consider the -160 C->A polymorphism an etiologic factor of diffuse gastric cancer in these patients since the frequency and type of genetic alterations of CDH1 are largely unknown in the Mexican population. It will be necessary to conduct epidemiologic studies in the Mexican population to determine the influence that genetic alterations have on the genesis of diffuse gastric carcinoma.

Adult↗
PubMed2006

Detection of novel single-nucleotide polymorphisms (SNPs) in the CYP21 gene and association analysis of two SNPs for CYP21 and ESR2 with litter size in a commercial sow population.

Altogether 129 F1 sows from a commercial sow farm with at least four litters were genotyped for the oestrogen receptor 2 gene (ESR2) and cytochrome P450 hydroxylase 21 gene (CYP21) and investigated for associations on the litter-size parameters: total number born and number born alive. Five novel polymorphisms were found in the 3'-untranslated region for the CYP21 gene. Genotype and allele frequencies for the CYP21 (position 3462G > A) single-nucleotide polymorphism (SNP) were 0.434 (GG), 0.504 (AG), 0.062 (AA) and 0.69 (G):0.31 (A), respectively. No association was found between this polymorphism and litter-size parameters. For the ESR2 gene, the SNP in exon 5 associated with an amino acid substitution MET (allele A) > VAL (allele G) was investigated. Only two genotypes were found leading to allele frequencies of 0.34 (A):0.66 (G). Only number born alive piglets were significantly increased for the AG genotype (p = 0.034) with 11.64 piglets per sow and litter in comparison with the GG genotype, leading to only 10.96 piglets per sow and litter. From these data, it can be concluded that the investigated SNP of the ESR2 gene is associated with the number of liveborn piglets in the commercial population considered, and hence could be useful in selection for litter size. Therefore, this gene should be investigated in additional populations.

Animals↗
PubMed2002

Search for and analysis of single nucleotide polymorphisms (SNPs) in rice (Oryza sativa, Oryza rufipogon) and establishment of SNP markers.

We searched for SNPs in 417 regions distributed throughout the genome of three Oryza sativa ssp. japonica cultivars, two indica cultivars, and a wild rice (O. rufipogon). We found 2800 SNPs in approximately 250,000 aligned bases for an average of one SNP every 89 bp, or one SNP every 232 bp between two randomly selected strains. Graphic representation of the frequency of SNPs along each chromosome showed uneven distribution of polymorphism-rich and -poor regions, but little obvious association with the centromere or telomere. The 94 SNPs that we found between the closely related cultivars 'Nipponbare' and 'Koshihikari' can be converted into molecular markers. Our establishment of 213 co-dominant SNP markers distributed throughout the genome illustrates the immense potential of SNPs as molecular markers not only for genome research, but also for molecular breeding of rice.

Genetic Markers↗
PubMed2000

New method for scanning of single-nucleotide polymorphisms (SNPs): recognition of guanine-guanine mismatches by dimeric naphthyridine.

Dimeric naphthyridine was designed and synthesized as a novel ligand that specifically binds to G-G mismatch, one of four SNP types. In the presence of dimeric naphthyridine, CD spectra of the G-G mismatch containing duplex noticeably changed, being accompanied by the induced CD at 300-350 nm, whereas no CD spectral change was observed for normal duplex. DNaseI footprinting titration indicated a selective binding of dimeric naphthyridine to the G-G mismatch with a dissociation constant of 53 nM.

Base Pair Mismatch↗
PubMed2001

Single nucleotide polymorphisms (SNPs) assay using reversible association and dispersion of DNA-linked colloidal nanoparticles.

The amphiphilic copolymer consisting of oligodeoxyribonucleotide (ODN; dT12) as the hydrophilic part and thermo-responsive poly(N-isopropylacrylamide) (polyNIPAAm) as the hydrophobic part was prepared. The copolymers formed DNA-linked colloidal nanoparticles above the phase transition temperature of polyNIPAAm part. The nanoparticles aggregated rapidly when the complementary ODN (dA12) was added into the dispersion. In contrast, they kept dispersed in the absence of the complementary ODN and in the presence of the point-mutated ODN ((dA6)dT(dA5)). These distinct phenomena may be applied for an oligonucleotides discrimination system in gene diagnosis.

Acrylic Resins↗
PubMed2004

Genotyping of single nucleotide polymorphisms (SNPs) influencing drug response by competitive allele-specific short oligonucleotide hybridization (CASSOH) with immunochromatographic strip.

Using competitive allele-specific oligonucleotide hybridization with immunochromatographic strip (CASSOH), we have developed a simplified method for the detection of eight polymorphisms that are especially important in the identification of drug responders or non-responders and patients at increased risk of drug toxicity. The genotyping method is unambiguously determined by the presence or the absence of visible purple lines on the immunochromatographic strip, and results are obtained within 5 min after PCR. This method is rapid, highly sensitive, simplified, and should be suitable for point-of-care genotyping in clinical settings.

Alleles↗
PubMed1999

Single nucleotide polymorphisms (SNPs) in the estrogen receptor gene and breast cancer susceptibility.

In order to evaluate the role of inherited variation in the estrogen receptor (ESR1) gene in human breast cancer, we determined intronic sequences flanking each ESRI exon; identified multiple SNPs and length polymorphisms in the ESR1 coding sequence, splice junctions and regulatory regions; and genotyped families at high risk of breast cancer and population-based breast cancer patients and controls. Of 10 polymorphic sites in ESR1, four are synonymous SNPs, two are nonsynonymous SNPs and four are length polymorphisms; five are novel. No ESR1 polymorphisms were associated with breast cancer, either in the high-risk families or the case-control study. We therefore conclude that inherited genetic variation is not a mechanism by which the estrogen receptor is commonly involved in breast cancer development.

5' Untranslated Regions↗
PubMed2004

The influence of neighboring-nucleotide composition on single nucleotide polymorphisms (SNPs) in the mouse genome and its comparison with human SNPs.

We analyzed the neighboring-nucleotide composition of 433,192 biallelic substitutions, representing the largest public collection of SNPs across the mouse genome. Large neighboring-nucleotide biases relative to the genome- or chromosome-specific average were observed at the immediate adjacent sites and small biases extended farther from the substitution site. For all substitutions, the biases for A, C, G, and T were 0.21, 2.63, 0.71, and -3.55%, respectively, on the immediate adjacent 5' site and -3.67, 0.75, 2.69, and 0.23%, respectively, on the immediate adjacent 3' side. Further examination of the six categories of substitution revealed that the neighboring-nucleotide patterns for transitions were strongly influenced by the hypermutability of dinucleotide CpG and the neighboring effects on transversions were complex. Probability of a transversion increased with increasing A + T content of the two immediate adjacent sites, which was similarly observed in the human and Arabidopsis genomes. Overall, the bias patterns for the neighboring nucleotides in the mouse and human genomes were essentially the same; however, the extent of the biases was notably less in mice. Our results provide the first comprehensive view of the neighboring-nucleotide effects in the mouse genome and are important for understanding the mutational mechanisms and sequence evolution in the mammalian genomes.

Animals↗
PubMed2002

Gene repair and mutagenesis mediated by chimeric RNA-DNA oligonucleotides: chimeraplasty for gene therapy and conversion of single nucleotide polymorphisms (SNPs).

Gene augmentation is an attractive and viable approach in treatment of inherited diseases, despite its limitations, such as the eliciting of host immune response, and the sustainability of gene expression. Therefore, alternative therapeutic approaches are being investigated, such as the use of chimeric RNA-DNA oligonucleotides (chimeraplasts), in which a mutated allele that already exists in an affected individual can be corrected. Although the only gene defects that can be corrected by chimeraplasty are point mutations, and the correction frequencies are variable, it has been observed that intracellular delivery of oligonucleotides is likely to be more efficient than that of plasmid DNA or viral vectors. Furthermore, corrected genes are expressed from their autologous promoters, thus ensuring correct spatial and temporal expression. Here we report on the recent progress made in the field of chimeraplasty, and the problems encountered.

Anemia, Sickle Cell↗
PubMed2005

SNPeffect: a database mapping molecular phenotypic effects of human non-synonymous coding SNPs.

Single nucleotide polymorphisms (SNPs) are an increasingly important tool for genetic and biomedical research. However, the accumulated sequence information on allelic variation is not matched by an understanding of the effect of SNPs on the functional attributes or 'molecular phenotype' of a protein. Towards this aim we developed SNPeffect, an online resource of human non-synonymous coding SNPs (nsSNPs) mapping phenotypic effects of allelic variation in human genes. SNPeffect contains 31 659 nsSNPs from 12 480 human proteins. The current release of SNPeffect incorporates data on protein stability, integrity of functional sites, protein phosphorylation and glycosylation, subcellular localization, protein turnover rates, protein aggregation, amyloidosis and chaperone interaction. The SNP entries are accessible through both a search and browse interface and are linked to most major biological databases. The data can be displayed as detailed descriptions of individual SNPs or as an overview of all SNPs for a given protein. SNPeffect will be regularly updated and can be accessed at http://snpeffect.vib.be/.

Alleles↗
PubMed1999

The essence of SNPs.

Single nucleotide polymorphisms (SNPs) are an abundant form of genome variation, distinguished from rare variations by a requirement for the least abundant allele to have a frequency of 1% or more. A wide range of genetics disciplines stand to benefit greatly from the study and use of SNPs. The recent surge of interest in SNPs stems from, and continues to depend upon, the merging and coincident maturation of several research areas, i.e. (i) large-scale genome analysis and related technologies, (ii) bio-informatics and computing, (iii) genetic analysis of simple and complex disease states, and (iv) global human population genetics. These fields will now be propelled forward, often into uncharted territories, by ongoing discovery efforts that promise to yield hundreds of thousands of human SNPs in the next few years. Major questions are now being asked, experimentally, theoretically and ethically, about the most effective ways to unlock the full potential of the upcoming SNP revolution.

DNA↗
PubMed2006

Integrating patterns of polymorphism at SNPs and STRs.

Single nucleotide polymorphisms (SNPs) and short tandem repeats (STRs) differ in mutation rate and mechanism. As a result of these differences, simultaneous consideration of polymorphism patterns at SNPs and STRs can provide insights that are difficult to obtain from analysis of either marker type in isolation. Here, we use coalescent simulations to model the opposing effects of contrasting mutational dynamics and of shared genealogical history on the correlation between polymorphism at linked SNPs and STRs. Results show that polymorphism patterns are correlated only weakly despite the shared underlying genealogy, underscoring the importance of divergent mutational processes. Examples illustrate how knowledge of these relationships could aid population genetic inference, indicating the need for thorough theoretical studies.

Animals↗
PubMed2006

A model-based approach to selection of tag SNPs.

BACKGROUND: Single Nucleotide Polymorphisms (SNPs) are the most common type of polymorphisms found in the human genome. Effective genetic association studies require the identification of sets of tag SNPs that capture as much haplotype information as possible. Tag SNP selection is analogous to the problem of data compression in information theory. According to Shannon's framework, the optimal tag set maximizes the entropy of the tag SNPs subject to constraints on the number of SNPs. This approach requires an appropriate probabilistic model. Compared to simple measures of Linkage Disequilibrium (LD), a good model of haplotype sequences can more accurately account for LD structure. It also provides a machinery for the prediction of tagged SNPs and thereby to assess the performances of tag sets through their ability to predict larger SNP sets. RESULTS: Here, we compute the description code-lengths of SNP data for an array of models and we develop tag SNP selection methods based on these models and the strategy of entropy maximization. Using data sets from the HapMap and ENCODE projects, we show that the hidden Markov model introduced by Li and Stephens outperforms the other models in several aspects: description code-length of SNP data, information content of tag sets, and prediction of tagged SNPs. This is the first use of this model in the context of tag SNP selection. CONCLUSION: Our study provides strong evidence that the tag sets selected by our best method, based on Li and Stephens model, outperform those chosen by several existing methods. The results also suggest that information content evaluated with a good model is more sensitive for assessing the quality of a tagging set than the correct prediction rate of tagged SNPs. Besides, we show that haplotype phase uncertainty has an almost negligible impact on the ability of good tag sets to predict tagged SNPs. This justifies the selection of tag SNPs on the basis of haplotype informativeness, although genotyping studies do not directly assess haplotypes. A software that implements our approach is available.

Databases, Genetic↗
PubMed2002

SNPper: retrieval and analysis of human SNPs.

MOTIVATION: Single Nucleotide Polymorphisms (SNPs) are an increasingly important tool for the study of the human genome. SNPs can be used as markers to create high-density genetic maps, as causal candidates for diseases, or to reconstruct the history of our genome. SNP-based studies rely on the availability of large numbers of validated, high-frequency SNPs whose position on the chromosomes is known with precision. Although large collections of SNPs exist in public databases, researchers need tools to effectively retrieve and manipulate them. RESULTS: We describe the implementation and usage of SNPper, a web-based application to automate the tasks of extracting SNPs from public databases, analyzing them and exporting them in formats suitable for subsequent use. Our application is oriented toward the needs of candidate-gene, whole-genome and fine-mapping studies, and provides several flexible ways to present and export the data. The application has been publicly available for over a year, and has received positive user feedback and high usage levels.

Database Management Systems↗
PubMed2006

SNPeffect v2.0: a new step in investigating the molecular phenotypic effects of human non-synonymous SNPs.

UNLABELLED: Single nucleotide polymorphisms (SNPs) constitute the most fundamental type of genetic variation in human populations. About 75 000 of these reported variations cause an amino acid change in the translated protein. An important goal in genomic research is to understand how this variability affects protein function, and whether or not particular SNPs are associated to disease susceptibility. Accordingly, the SNPeffect database uses sequence- and structure-based bioinformatics tools to predict the effect of non-synonymous SNPs on the molecular phenotype of proteins. SNPeffect analyses the effect of SNPs on three categories of functional properties: (1) structural and thermodynamic properties affecting protein dynamics and stability (2) the integrity of functional and binding sites and (3) changes in posttranslational processing and cellular localization of proteins. The search interface of the database can be used to search specifically for polymorphisms that are predicted to cause a change in one of these properties. Now based on the Ensembl human databases, the SNPeffect database has been remodeled to better fit an automatically updatable structure. The current edition holds the molecular phenotype of 74 567 nsSNPs in 23 426 proteins. AVAILABILITY: SNPeffect can be accessed through http://snpeffect.vib.be.

Algorithms↗
PubMed2002

Conducting and putting science into practice: the future of oral health research, dental education, and dental practice.

Popular attention has focused on connections between single nucleotide polymorphisms (SNPs) where single genome irregularities are associated with biological deficiencies. The more significant and more difficult work will come through seeking to understand the proteonomics--the way sets of genes are expressed as proteins, and ultimately in larger and more complex entities. Future developments will take place at the interfaces among various disciplines. We are already seeing the introduction of diagnostic tests based on the new genomics in dental offices. New skills will be needed to bring these emerging developments into practice.

Dental Research↗
PubMed2003

Effects of electron-beam irradiation on buccal-cell DNA.

Buccal cells were collected from 29 participants, by use of mouthwash rinses, and were split into equal aliquots, with one aliquot irradiated by electron-beam (E-beam) irradiation equivalent to the sterilizing dosage used by the U.S. Postal Service and the other left untreated. Aliquots were extracted and tested for DNA yields (e.g., TaqMan assay for quantifying human genomic DNA), genomic integrity, and amplification-based analysis of genetic variants (e.g., single-nucleotide polymorphisms [SNPs] and single tandem repeats [STRs]). Irradiated aliquots had lower median DNA yields (3.7 microg/aliquot) than untreated aliquots (7.6 microg/aliquot) (P<.0005) and were more likely to have smaller maximum DNA fragment size, on the basis of genomic integrity gels, than untreated aliquots (P<.0005). Irradiated aliquots showed poorer PCR amplification of a 989-bp beta-globin target (97% for weak amplification and 3% for no amplification) than untreated aliquots (7% for weak amplification and 0% for no amplification) (P<.0005), but 536-bp and 268-bp beta-globin targets were amplified from all aliquots. There was no detectable irradiation effect on SNP assays, but there was a significant trend for decreased detection of longer STRs (P=.01) in irradiated versus untreated aliquots. We conclude that E-beam irradiation reduced the yield and quality of buccal-cell specimens, and, although irradiated buccal-cell specimens may retain sufficient DNA integrity for some amplified analyses of many common genomic targets, assays that target longer DNA fragments (>989 bp) or require whole-genome amplification may be compromised.

Bioterrorism↗