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At least 163 records · Page 9Linked to original sources
PubMed2003

[Polymorphism of two novel SNPs, which locate on chromosome 9p21-22, in Han Chinese of Hunan].

OBJECTIVE: To search novel SNPs in exons and regulatory regions of CDKN2A and two novel putative tumor suppressor genes NGX6 and UBAP1, which all reside on chromosome 9p21-22. METHODS: The exons and regulatory regions of those genes were amplified and sequenced in 96 subjects. RESULTS: Two novel SNPs were found, one resides on the sixth exon of UBAP1 gene and the other on the fourth exon of CDKN2A gene. Two novel SNPs were submitted to the dbSNP database, and their access ID are rs3135929 and rs3088440. The polymorphic information contents of them are 0.102 and 0.213 respectively. There is linkage equilibrium between them, and the polymorphic information content of their haplotype is 0.302, higher than any of them individually. CONCLUSION: The polymorphic information content can be improved by using haplotype analysis of several SNPs.

Asian People↗
PubMed2003

SNPCEQer II: the integrated detection and analysis of SNPs in DNA sequences.

SNPCEQer II is a graphical user interface (GUI)-based application that integrates single nucleotide polymorphism (SNP) detection, SNP analysis and SNP editing in the Microsoft Windows (R) environment. SNPCEQer II detects SNPs in DNA sequences generated by the Beckman CEQ TM 2000 XL DNA analysis system. It provides tools to analyse SNPs by inspecting and comparing trace data (chromatograms) around putative SNPs with that of other related DNA sequences, and it can search for those SNPs in the National Center for Biotechnology Information (NCBI) databases. SNPCEQer II can determine the mutation type of a coding SNP and generate data for submission to the dbSNP database. The SNP report can be edited and printed, as can the chromatograms. SNPCEQer II is implemented in Visual C++.

Algorithms↗
PubMed2006

[Screening and analysis of coding SNPs of HLA-DQA1 gene involved in susceptibility for cervical cancer].

BACKGROUND & OBJECTIVE: Polymorphisms of human leukocyte antigen (HLA) gene play an important role in the development of cervical cancer. This study was to screen single nucleotide polymorphisms (SNPs) of HLA-DQA1 gene involved in susceptibility of cervical cancer by a bioinformatics approach, and analyze their correlations to abnormal gene functions. METHODS: SNPs of HLA-DQA1 were screened from a public database dbSNP by SNPper software, and relevant FASTA subsequences were also obtained from dbSNP. PARSESNP software was used to analyze cSNPs. RESULTS: Two SNPs, rs9272693 and rs9272703, which may induce mis-sense mutation, were identified in codon region of HLA-DQA1 gene. A PSSM difference>10 was used to predict deleterious mutation. CONCLUSIONS: SNPper software in combination with PARSESNP software could be used to analyze SNPs of HLA-DQA1 gene and select the variants in a conserved region, and it provides an evaluation criterion. But the results need to be verified in cervical cancer patients and control populations.

Databases as Topic↗
PubMed2001

The single-nucleotide polymorphism lottery: how useful are a few common SNPs in identifying disease-associated alleles?

It has been proposed that using association analysis of single nucleotide polymorphism (SNP) markers in candidate genes may be more successful in identifying disease susceptibility genes for complex diseases. Finding all the SNPs within a candidate gene and genotyping a large case-control cohort is a resource-intensive process. As linkage disequilibrium extends across small regions of the genome, the expectation is that a few common anonymous SNPs will be sufficient to detect functional disease-associated alleles. The aim of this investigation was to compare the ability of a number of family- and population-based association methods to identify known susceptibility loci using the Genetic Analysis Workshop 12 simulated data set. As expected, case-control methods were more likely to detect association with individual SNPs but family-based haplotyping methods appeared better able to localize the position of functional polymorphism.

Adult↗
PubMed2005

Characterization of linkage disequilibrium structure, mutation history, and tagging SNPs, and their use in association analyses: ELAC2 and familial early-onset prostate cancer.

In association analyses, it is critical that informative single-nucleotide polymorphisms (SNPs) be selected for study and utilized appropriately. We sequenced 38 kb, including exons of ELAC2, promoter region and conserved upstream intergenic sequences. A comprehensive characterization of linkage disequilibrium (LD) structure and mutation history was performed using our principal components analysis (PCA) method and a phylogenetic analysis. We identified a complex pattern of LD structure consistent with the occurrence of both recombination and mutation events within ELAC2. Four overlapping and noncontiguous LD groups were defined. Eight tagging SNPs (tSNPs) were identified, accounting for over 90% of the genetic variation of the 19 total variants. We tested associations between familial early-onset prostate cancer (PRCA) and each variant independently and in haplotypes. We performed these tests using all 19 variants and the 8 tSNPs; the results using tSNP haplotypes accurately represent the association evidence for the full haplotypes. We observed increased evidence for association when SNPs were analyzed in haplotypes. The phylogenetic analysis indicated three haplotypes, clustered farthest from the root-node, all of which were found more often in cases than controls. These three haplotypes together showed the best evidence of association with familial, early-onset PRCA (P=0.0024; odds ratio=2.23; 95% CI, 1.33-3.74), indicating possible allelic heterogeneity. Our results suggest that 8 tSNPs are required to comprehensively assess associations in ELAC2, and that haplotypes should be considered for analysis, and that a knowledge of mutation history may be helpful in parsing allelic heterogeneity and suggesting combinations of haplotypes to be tested.

Aged↗
PubMed2002

Analysis of SNPs and other genomic variations using gel-based chips.

Application of microarrays for the analysis of point mutations and SNPs in genomic DNAs is currently under intensive development. Various technologies are being investigated, employing enzymatic, chemical, and physical tools [for review, see Tillib and Mirzabekov, 2001]. Our current approach is based on the use of IMAGE chips (immobilized microarrays of gel elements) consisting of an array of gel pads attached to a hydrophobic glass surface. The gel pads range in size from picoliters to nanoliters and are used for immobilization of oligonucleotide probes, as well as miniature test tubes for chemical or enzymatic reactions with tethered compounds. Nucleic acids are hybridized, fractionated, modified, and subjected to enzymatic reactions inside the pads. All steps of sequence analysis (PCR-amplification, activation or release of primers and products, DNA extension, hybridization, and reading of the results) can be performed within the same pad. A flexible and inexpensive technology platform enables one to monitor processes in the arrays in both real time and steady-state. Identification of SNPs, microsequencing, and other specific tasks are easily performed. In particular, stacking interactions with short oligonucleotides enhance the capability of high-throughput screening. The IMAGE chips can be analyzed using a variety of equipment, from a dedicated multi-color fluorescent microscope or MALDI-spectrometer to an inexpensive portable analyzer suitable for field conditions. Customized gel-based chips were successfully used for screening of SNPs in a broad range of biologically meaningful genes.

Alleles↗
PubMed2001

A semi-automated system for analysis and storage of SNPs.

The discovery of single nucleotide polymorphisms ( SNPs) is currently pursued with a tremendous effort. SNPs represent a rich source for molecular markers, since estimations predict six to seven million of these DNA variations in the human genome. A subset of these genetic variants is thought to have a pervasive impact on modern medicine, be it for the elucidation of differential pharmacological response or for the facilitated identification of genes involved in monogenetic and complex human diseases. Here we describe the overall process that leads to the set up of a SNP database. We describe a high-throughput sequencing assay for SNP discovery, automation of the dataflow from the DNA sequencer to the SNP analysis, and the tools to facilitate it. At the end of the process, a web-accessible interface collects the SNP information, which is processed in order to be written into the SNP database and to be available for end users who would like to select appropriate SNPs for their special screening needs.

Automation↗
PubMed2004

Bayesian approach to discovering pathogenic SNPs in conserved protein domains.

The success rate of association studies can be improved by selecting better genetic markers for genotyping or by providing better leads for identifying pathogenic single nucleotide polymorphisms (SNPs) in the regions of linkage disequilibrium with positive disease associations. We have developed a novel algorithm to predict pathogenic single amino acid changes, either nonsynonymous SNPs (nsSNPs) or missense mutations, in conserved protein domains. Using a Bayesian framework, we found that the probability of a microbial missense mutation causing a significant change in phenotype depended on how much difference it made in several phylogenetic, biochemical, and structural features related to the single amino acid substitution. We tested our model on pathogenic allelic variants (missense mutations or nsSNPs) included in OMIM, and on the other nsSNPs in the same genes (from dbSNP) as the nonpathogenic variants. As a result, our model predicted pathogenic variants with a 10% false-positive rate. The high specificity of our prediction algorithm should make it valuable in genetic association studies aimed at identifying pathogenic SNPs.

Algorithms↗
PubMed2005

InSNP: a tool for automated detection and visualization of SNPs and InDels.

Availability of high quality SNP data is a rate-limiting factor in understanding the impact of genetic variability on gene function and phenotype. Although global projects like HAPMAP generate large numbers of SNPs in an even spacing throughout the human genome, many variation studies have a more focused approach: in the follow-up of positional association findings, candidate gene studies, and functional genomics experiments, knowledge of all variations in a limited amount of sequence (e.g., a gene) is needed. This leads to a large number of resequencing experiments, for which there is a surprising lack of analysis software. We have thus developed specialized software (InSNP) for targeted mutation detection and compared its performance to Polyphred and Mutation Surveyor using 28 amplicons. Out of a total of 579 (InSNP), 644 (Polyphred), and 526 (Mutation Surveyor) SNP predictions, 39 SNPs were confirmed by human expert inspection, with five SNPs missed by Polyphred and one missed by InSNP using the default settings. For InDel detection, out of 70 (InSNP), 28 (Polyphred), and 693 (Mutation Surveyor) InDel predictions, two InDels were confirmed by human expert inspection, with one InDel missed by Polyphred. InSNP provides a user-friendly interface with better functionality for mutation detection than general-purpose sequence handling software. It provides similar SNP detection sensitivity and specificity as the public domain and commercial alternatives in the investigated dataset. We hope that InSNP lowers the barriers to the use of automated mutation detection software and aids in the improvement of the efficiency of such experiments. The Windows installer (setup) program and sample datasets are available at www.mucosa.de/insnp/.

Algorithms↗
PubMed2006

Distribution of human SNPs and its effect on high-throughput genotyping.

Utilizing the results of extensive single nucleotide polymorphism (SNP) studies in humans, stimulated by the International HapMap Project, we present evidence that SNPs are not randomly spaced across the genome, but are somewhat clustered. This observation has important consequences for assay design, since hidden variants in primer sites can affect the accuracy of data. Indeed, using data from the calibration exercises of the HapMap Project, we found instances in which primer site mutations caused allele dropout and other genotyping failures. Given the dynamic nature of SNP discovery, it was inevitable that SNPs would be identified in the primer sites of many assays used for HapMap genotyping. We found that assays with such primer site mutations were correlated with elevated rates of genotype failure and allele dropout. This suggests that taking nearby SNPs into account is important for optimal genotyping assay design.

Alleles↗
PubMed2006

Nonsynonymous SNPs: validation characteristics, derived allele frequency patterns, and suggestive evidence for natural selection.

We experimentally investigated more than 1,200 entries in dbSNP that would change amino-acids (nsSNPs), using various subsets of DNA samples drawn from 18 global populations (approximately 1,000 subjects in total). First, we mined the data for any SNP features that correlated with a high validation rate. Useful predictors of valid SNPs included multiple submissions to dbSNP, having a dbSNP validation statement, and being present in a low number of ESTs. Together, these features improved validation rates by almost 10-fold. Higher-abundance SNPs (e.g., T/C variants) also validated more frequently. Second, we considered derived alleles and noted a considerably (approximately 10%) increased average derived allele frequency (DAF) in Europeans vs. Africans, plus a further increase in some other populations. This was not primarily due to an SNP ascertainment bias, nor to the effects of natural selection. Instead, it can be explained as a drift-based, progressive increase in DAF that occurs over many generations and becomes exaggerated during population bottlenecks. This observation could be used as the basis for novel DAF-based tests for comparing demographic histories. Finally, we considered individual marker patterns and identified 37 SNPs with allele frequency variance or FST values consistent with the effects of population-specific natural selection. Four particularly striking clusters of these markers were apparent, and three of these coincide with genes/regions from among only several dozen such domains previously suggested by others to carry signatures of selection.

Alleles↗
PubMed2001

SNPs, protein structure, and disease.

Inherited disease susceptibility in humans is most commonly associated with single nucleotide polymorphisms (SNPs). The mechanisms by which this occurs are still poorly understood. We have analyzed the effect of a set of disease-causing missense mutations arising from SNPs, and a set of newly determined SNPs from the general population. Results of in vitro mutagenesis studies, together with the protein structural context of each mutation, are used to develop a model for assigning a mechanism of action of each mutation at the protein level. Ninety percent of the known disease-causing missense mutations examined fit this model, with the vast majority affecting protein stability, through a variety of energy related factors. In sharp contrast, over 70% of the population set are found to be neutral. The remaining 30% are potentially involved in polygenic disease.

Allosteric Regulation↗
PubMed2001

Characterization of publicly available SNPs in the Korean population.

Single-nucleotide polymorphisms (SNPs) are the most abundant form of genetic variations and have a great potential for mapping studies of complex genetic traits. Currently a great deal of effort is invested in the identification of SNPs, and a large volume of data is already available through public databases (NCBI, NCI, WICGR, HGBASE). For an association mapping study, SNP allele frequencies in the population are critical. As an initial step toward construction of an SNP database of the Korean population, we have determined the allele frequencies of 300 cSNPs selected from the public database in 24 individuals. Among the tested markers, approximately 23% did not show polymorphism in the population. The results suggest that the ethnic and population based differences should be considered in the selection of SNPs for the study of complex diseases with association mapping methods.

Alleles↗
PubMed2007

Sub-populations within the major European and African derived haplogroups R1b3 and E3a are differentiated by previously phylogenetically undefined Y-SNPs.

Single nucleotide polymorphisms on the Y chromosome (Y-SNPs) have been widely used in the study of human migration patterns and evolution. Potential forensic applications of Y-SNPs include their use in predicting the ethnogeographic origin of the donor of a crime scene sample, or exclusion of suspects of sexual assaults (the evidence of which often comprises male/female mixtures and may involve multiple perpetrators), paternity testing, and identification of non- and half-siblings. In this study, we used a population of 118 African- and 125 European-Americans to evaluate 12 previously phylogenetically undefined Y-SNPs for their ability to further differentiate individuals who belong to the major African (E3a)- and European (R1b3, I)-derived haplogroups. Ten of these markers define seven new sub-clades (equivalent to E3a7a, E3a8, E3a8a, E3a8a1, R1b3h, R1b3i, and R1b3i1 using the Y Chromosome Consortium nomenclature) within haplogroups E and R. Interestingly, during the course of this study we evaluated M222, a sub-R1b3 marker rarely used, and found that this sub-haplogroup in effect defines the Y-STR Irish Modal Haplotype (IMH). The new bi-allelic markers described here are expected to find application in human evolutionary studies and forensic genetics.

Black People↗
PubMed2002

SNP genotyping using a simple and rapid single-tube modification of ARMS illustrated by analysis of 6 SNPs in a population of males with FRAXA repeat expansions.

Microsatellites have been used extensively in gene mapping, linkage and association studies but with the near completion of the human genome project (HGP) single nucleotide polymorphisms (SNP) have become the marker of choice. However, for association studies to be useful large numbers of SNPs must be analysed. To make these studies cost effective a simple and non-labour intensive method for SNP genotyping is essential. This work describes a single-tube modification of the amplification refractory mutation system (Biallelic-ARMS). Control amplimers flanking the SNP were amplified in a single-tube multiplex PCR with two SNP specific primers that prime in opposite directions. The SNP allele was identified on the basis of PCR product size after gel electrophoresis. Biallelic-ARMS was used to analyse six SNPs within 300 kb of the FRAXA repeat, two from the HGP SNP Database (ATL1 and FMRb) and four novel SNPs (WEX1, WEX10, WEX17 and WEX28). The study population consisted of 649 males with a range of FRAXA (10 to >200) repeat sizes. Each SNP correlated with distinct haplogroups, as identified by DXS548, FRAXAC1 and FRAXAC2 flanking microsatellite repeat patterns and confirmed the initial choice of haplogroups for FRAXA repeat stability defined by Enniset al.

Alleles↗
PubMed2005

Association of the HLA region with multiple sclerosis as confirmed by a genome screen using >10,000 SNPs on DNA chips.

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system, with a complex genetic background. Here, we present a genome screen for association in small scale, employing 11,555 single nucleotide polymorphisms (SNPs) on DNA chips for genotyping 100 MS patients stratified for HLA-DR2+ and 100 controls. More than 500 SNPs revealed significant differences between cases and controls before Bonferroni correction. A fraction of these SNPs was reanalysed in two additional cohorts of patients and controls, using high-throughput genotyping methods. A marker on chromosome 6p21.32 (rs2395182) yielded the highest significance level, validating the established HLA-DR association.

Genetic Linkage↗
PubMed2006

Biased distribution of single nucleotide polymorphisms (SNPs) in porcine Toll-like receptor 1 (TLR1), TLR2, TLR4, TLR5, and TLR6 genes.

Toll-like receptors (TLRs) recognize various microbial components and induce immune responses. Polymorphisms in TLRs may influence their recognition of pathogen-derived molecules; swine TLRs are predicted to be associated with responses to infectious diseases such as pneumonia. In this study, we searched for single nucleotide polymorphisms (SNPs) in the coding sequences of porcine TLR1, TLR2, TLR4, TLR5, and TLR6 genes in 96 pigs from 11 breeds and elucidated 21, 11, 7, 13, and 11 SNPs, respectively, which caused amino acid substitutions in the respective TLRs. Distribution of these nonsynonymous SNPs was biased; many were located in the leucine-rich repeats, particularly in TLR1. These data demonstrated that the heterogeneity of TLR genes was preserved in various porcine breeds despite intensive breeding that was carried out for livestock improvement. It suggests that the heterogeneity in TLR genes is advantageous in increasing the possibility of survival in porcine populations.

Animals↗
PubMed2003

Rapid screening of mtDNA coding region SNPs for the identification of west European Caucasian haplogroups.

This work presents a selection of 16 SNPs from the coding region of the human mitochondrial DNA. The selected markers are used for the assignment of individuals to one of the nine major European Caucasian mitochondrial haplogroups. The selected SNPs are targeted in two multiplex systems, via the application of the SNaPshot kit, a multiplex method based on the dideoxy single-base extension of unlabeled oligonucleotide primers. The method is conceived as a rapid screening technique prior to sequencing analysis, in order to eliminate multiple suspects from an inquiry or to discriminate between stains in a high volume casework example. Moreover, the ability to assign an unknown sample to an mtDNA type of known Caucasian origin could be of probative value in some investigations. A database of 277 Austrian Caucasians has been constructed, and the probability of a chance match between two unrelated individuals is calculated as 11.4%. This novel multiplex PCR amplification and typing system for mtDNA coding region SNPs promises to be a convenient and informative new DNA profiling system in the forensic field.

DNA, Mitochondrial↗