PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “single nucleotide variation”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 37 records · Page 2Linked to original sources

Deep clinical and genetic analysis of 17p13.3 region: 38 pediatric patients diagnosed using next-generation sequencing and literature review.

BACKGROUND: Chromosome 17p13.3 is a region of genomic instability associated with different neurodevelopmental diseases. The malformation spectrum of 17p13.3 microdeletions ranges from an isolated lissencephaly sequence to Miller-Dieker syndrome, while 17p13.3 microduplications result in autism, learning disabilities, microcephaly and other brain malformations. This study aims to provide a more comprehensive delineation of the clinical and genetic characteristics associated with 17p13.3 alterations. METHODS: We retrospectively analyzed the next-generation sequencing (NGS) data of more than 40 thousand patients from January 2016 to December 2021 and identified 38 pediatric patients with copy-number variations (CNVs) or single-nucleotide variations (SNVs) in 17p13.3 region. Published patients with CNVs in the 17p13.3 region were also collected and we performed a Chi-square test to compare the phenotype spectrum of microdeletions and microduplications. RESULTS: Among the 27 CNV patients, 20 patients with microdeletions and 7 patients with microduplications were found. PAFAH1B1 was the most frequently deleted gene and CRK was the most frequently duplicated gene. Affected genes in 11 SNV patients included PAFAH1B1 and PRPF8. Developmental delay was the most common abnormality detected in the 38 patients (29/38, 76.3%). Of note, Case 10 presented omphalocele and Case 23 presented scoliosis, webbed neck and bone cyst, all of which were unusual variant phenotypes in this region. The Chi-square test revealed that epilepsy, lissencephaly and short stature were statistically significant with microdeletions, while behavioral abnormalities and hand and foot abnormalities were significant with microduplications (p&#x2009;<&#x2009;0.01). CONCLUSIONS: While PAFAH1B1, YWHAE and CRK are associated with major phenotypes of 17p13.3, RTN4RL1 may be involved in white matter changes and HIC1 might contribute to the occurrence of omphalocele. This study provided a comprehensive understanding of genetic information and phenotype spectrum of the 17p13.3 region.

Humans↗

Identification of single nucleotide polymorphisms in the human kallikrein 10 (KLK10) gene and their association with prostate, breast, testicular, and ovarian cancers.

BACKGROUND: The KLK10 gene (also known as the normal epithelial cell-specific 1 gene) is a member of the expanded human kallikrein gene family. Recently, it has been reported that KLK10 is a tumor suppressor gene and that its expression is downregulated in various forms of cancer and cancer cell lines. KLK10 is also upregulated in ovarian cancer. We thus hypothesized that the KLK10 gene may be a target for mutations in various cancers. METHODS: We sequenced the five coding exons of the KLK10 gene using genomic DNA from various tumors, normal tissues, and blood, by PCR amplification and automated sequencing. RESULTS: In none of the tumor-derived DNAs, we identified somatic mutations that could inactivate this gene. However, we identified a prevalent germline single nucleotide variation at codon 50 (exon 3) of this gene [GCC (alanine) to TCC (serine)]. The GCC genotype was less prevalent in prostatic cancer patients in comparison to control subjects (P = 0.027) but no differences were seen with testicular, ovarian, and breast cancer. We also identified four genetic variations in exon 4, at codons106 [GGC (glycine) to GGA (glycine)], codon 112 [ACG (threonine) to ACC (threonine)], codon 141 [CTA (leucine) to CTG (leucine)], and at codon 149 [CCG (proline) to CTG (leucine)]. None of these variations was significantly different between normal subjects and cancer groups. CONCLUSIONS: We found no evidence for somatic mutations of the KLK10 gene in cancers of the prostate, breast, ovary, and testis. The single nucleotide variation at codon 50 appears to be associated with prostate cancer risk.

Breast Neoplasms↗

Multiplex genotyping of the human beta2-adrenergic receptor gene using solid-phase capturable dideoxynucleotides and mass spectrometry.

Previously, we established the feasibility of using solid phase capturable (SPC) dideoxynucleotides to generate single base extension (SBE) products which were detected by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for multiplex genotyping, an approach that we refer to as SPC-SBE. We report here the expanding of the SPC-SBE method as a single-tube assay to simultaneously detect 20 single nucleotide variations in a model system and 3 single nucleotide polymorphisms (SNPs) in the human beta2-adrenergic receptor (beta2AR) gene. Twenty primers were designed to have a sufficient mass difference between all extension products for accurate detection of nucleotide variants of the synthetic templates related to the p53 gene. These primers were extended simultaneously in a single tube with biotin-ddNTPs to generate 3(')-biotinylated DNA products, which were first captured by streptavidin-coated magnetic beads and then released from the beads and analyzed with MALDI-TOF MS. This approach generates a mass spectrum free of primer peaks and their associated dimers, increasing the scope of multiplexing SNPs. We also simultaneously genotyped 3 SNPs in the beta2AR gene (5(')LC-Cys19Arg, Gly16Arg, and Gln27Glu) from the genomic DNA of 20 individuals. Comparison of this approach with direct sequencing and the restriction fragment length polymorphism method indicated that the SPC-SBE method is superior for detecting nucleotide variations at known SNP sites.

Base Sequence↗

[Use of phage display for detecting single-nucleotide differences in genes].

Experimental strategy has been developed for selection of mismatched DNA binding phages from library of E. coli f1 filamentous phages carrying random peptide inserts on the surface of bacteriophage particles. The strategy is based on the use of phage display technique, DNA heteroduplexes (with single nucleotide variations), and paramagnetic beads. DNA heteroduplexes have been obtained from biotin-labeled PCR product. During the first stage the phage particles were incubated with DNA heteroduplexes possessing mismatched nucleotides. The next step after elimination of free phages and separation of bound phages from DNA heteroduplexes was subtraction of phages binding with DNA heteroduplexes (without mismatched nucleotides). Phages selected by this method were capable of discriminating DNA heteroduplexes with single nucleotide variations from DNA homoduplexes. Phages immobilized on solid base retain their activity and specificity, and therefore can be used for developing a new screening automated method for detecting point mutations and gene polymorphism.

Base Sequence↗

A single-nucleotide natural variation (U4 to C4) in an influenza A virus promoter exhibits a large structural change: implications for differential viral RNA synthesis by RNA-dependent RNA polymerase.

The influenza A virus promoter is recognized by the influenza A virus RNA-dependent RNA polymerase, and directs both transcription and replication of the viral RNA genome. Within the sequence of this promoter, flu strains exhibit a natural, unique variation, either a U or a C, at the fourth position from the 3' end. Promoters that contain a C residue (C4 promoter), which are invariably found in genome segments that encode the three RNA polymerase subunits (PB1, PB2 and PA), down-regulate transcription but activate genome replication. Here, we have determined the structure of the C4 promoter by NMR spectroscopy and compared it with the structure of the U4 promoter, which was determined previously. The structure of the internal loop in the C4 promoter is similar to that of the U4 promoter. However, the terminal stem of the C4 promoter is strikingly different from that of the U4 promoter. These structural data suggest that the internal loop is important for polymerase binding to the promoter, and the terminal stem is crucial for differential regulation of transcription and replication.

Base Sequence↗

Characterization of frequencies and distribution of single nucleotide insertions/deletions in the human genome.

Most of the studies on single nucleotide variations are on substitutions rather than insertions/deletions. In this study, we examined the distribution and characteristics of single nucleotide insertions/deletions (SNindels), using data available from dbSNP for all the human chromosomes. There are almost 300,000 SNindels in the database, of which only 0.8% are validated. They occur at the frequency of 0.887 per 10 kb on average for the whole genome, or approximately 1 for every 11,274 bp. More than half occur in regions with mononucleotide repeats the longest of which is 47 bases. Overall the mononucleotide repeats involving C and G are much shorter than those for A and T. About 12% are surrounded by palindromes. There is general correlation between chromosome size and total number for each chromosome. Inter-chromosomal variation in density ranges from 0.6 to 21.7 per kilobase. The overall spectrum shows very high proportion of SNindel of types -/A and -/T at over 81%. The proportion of -/A and -/T SNindels for each chromosome is correlated to its AT content. Less than half of the SNindels are within or near known genes and even fewer (<0.183%) in coding regions, and more than 1.4% of -/C and -/G are in coding compared to 0.2% for -/A and -/T types. SNindels of -/A and -/T types make up 80% of those found within untranslated regions but less than 40% of those within coding regions. A separate analysis using the subset of 2324 validated SNindels showed slightly less AT bias of 74%, SNindels not within mononucleotide repeats showed even less AT bias at 58%. Density of validated SNindels is 0.007/10 kb overall and 90% are found within or near genes. Among all chromosomes, Y has the lowest numbers and densities for all SNindels, validated SNindels, and SNindels not within repeats.

Base Pairing↗

Discovery, scoring and utilization of human single nucleotide polymorphisms: a multidisciplinary problem.

There are great hopes that the most common form of human genetic variation, single nucleotide polymorphisms (SNPs), can be used to improve radically biological understanding and to advance medicine. However, considerable controversy exists over just how SNPs can be applied to gain these insights. The second international SNP meeting, held at Schloss Hohenkammer, Munich, Germany, brought together leading international scientists from academia and industry to look at these issues from a multidisciplinary perspective. Topics that were covered spanned SNP discovery, scoring technologies, population genetics, disease studies, commercial dimensions, pharmacogenomics, bioinformatics, and legal considerations. SNP discovery is picking up speed; The SNP Consortium (TSC) is set to produce 300,000 publicly available SNPs within 2 years. Improved technologies for scoring SNPs are reducing hands-on time and cost, although truly high-throughput methods are still lacking for genome-wide population-based studies. Large numbers of SNPs have already been analysed in diverse populations. The results emphasise the importance of considering population history when using SNPs to search for genetic risk factors. Opinions on the feasibility of extensive SNP-based analysis of complex disease vary. However, combining expertise from several fields will be key to achieving optimal utilization of SNPs.

Humans↗

Characterization of phosphorylation variants for identifying adaptive alleles in Zea.

Large-scale genome sequencing of maize wild species (teosinte) has uncovered thousands of genetic mutations, but distinguishing causal alleles from neutral variations remains a significant challenge. In this study, we conducted a comprehensive analysis of phosphorylation-associated single-nucleotide variations (pSNVs) to enhance our understanding of adaptive variations in the Zea genus. We collected 234 teosinte genomes from seven different taxa and 507 cultivated maize genomes to identify single-nucleotide variants that target phosphorylation machinery, which is crucial for plant development and environmental adaptation. Our analysis identified 33&#x2009;687 pSNVs within the Zea genus and revealed a reduction in genetic conservation along with an increase in protein abundance and expression for genes harboring pSNVs. Additionally, pSNVs present stronger purifying selection pressures compared with other missense mutations. We found that maize possesses fewer pSNVs than teosinte, likely due to the effects of selection and hitchhiking. By examining the role of pSNVs related to kinase-substrate rewriting events and exhibiting evolutionary divergence jointly, our results suggest that pSNVs impact multiple traits, particularly flowering time variation between teosinte and maize. Furthermore, we documented the widespread presence of pSNVs in Arabidopsis thaliana, rice, and wheat, identifying 46 pSNVs that have convergently evolved between maize and other species. Our study provides another insight into uncovering adaptive alleles in wild species by incorporating protein signaling sites and emphasizes the potential of utilizing wild species for future crop improvement.

Zea mays↗

Genetic variations and haplotypes of CYP2C19 in a Japanese population.

Forty-eight single nucleotide variations, including 27 novel ones, were found in the 5'- regulatory region, all of the exons and their surrounding introns of CYP2C19 in 253 Japanese subjects (134 diabetic patients and 119 healthy volunteers). Identified novel variations were as follows: -2772G>A, 2767_-2760delGGTGAACA, -2720T>C, -2547delG, -2545G>T, -2545_-2544 delGC, and -2040C>T in the enhancer region; -778C>T, -777G>A, -529G>C, -189C>A, and -185A>G in the promoter region; 151A>G (S51G), 481G>C (A161P), 986G>A (R329H), 1078G>A (D360N), and 1119C>T (D373D) in the exons, and IVS1+128T>A, IVS3+163G>A, IVS4+271A>G, IVS5-49A>G, IVS6-210C>T, IVS6-196T>A, IVS6-32T>A, IVS7+84G>A, IVS7-174C>T, and IVS8+64C>T in the introns. Since we found no significant differences in the variation frequencies between healthy volunteers and diabetic patients, the data for all subjects were treated as one group in further analysis. The allele frequencies were 0.265 for IVS6-196T>A, 0.045 for -2772G>A and -2720T>C, 0.024 for -2040C>T, 0.014 for IVS7-174C>T, 0.010 for -529G>C, 0.006 for IVS1+128T>A and 481G>C (A161P), 0.004 for -2767_-2760delGGTGAACA and IVS6-210C>T, and 0.002 for the other 17 variations. In addition, the two known nonsynonymous single nucleotide polymorphisms, 681G>A (splicing defect, (*)2 allele) and 636G>A (W212X; (*)3 allele) were detected at 0.267 and 0.128 frequencies, respectively. No variation was detected in the known binding sites for constitutive androstane receptor and glucocorticoid receptor. Linkage disequilibrium analysis showed several close linkages of variations throughout the gene. By using the variations, thirty-one haplotypes of CYP2C19 and their frequencies were estimated. Our results would provide fundamental and useful information for genotyping CYP2C19 in the Japanese and probably other Asian populations.

Aryl Hydrocarbon Hydroxylases↗

Single-strand conformation polymorphism (SSCP) analysis as a tool for viroid characterisation.

The potential of routine single-strand conformation polymorphism (SSCP) analysis for viroid characterization has been evaluated. Electrophoresis of 311 cloned full length viroid DNA inserts recovered from a field isolate of citrus exocortis viroid (CEVd) showed shifts in the migration of the cDNA or/and hDNA strands in non-denaturing 14% polyacrylamide gels. Using a single set of electrophoresis conditions seven different groups of variants (containing one to six changes), which did not represent the overall variability among clones, were identified. The relationship between the different SSCP profiles observed among clones and the variation in their nucleotide sequences was confirmed by sequence analysis. Variations in the dimensions of the gel allowed higher resolution and therefore the detection of additional single nucleotide variations among clones initially clustered into the same group. The viroid region affected by specific changes could be established by SSCP analysis of partial viroid length DNA. The potential use of SSCP analysis as a tool to screen existing viroid populations in infected hosts prior to sequencing is discussed.

Base Sequence↗

A homogeneous, ligase-mediated DNA diagnostic test.

Single-nucleotide variations are the most widely distributed genetic markers in the human genome. A subset of these variations, the substitution mutations, are responsible for most genetic disorders. As single nucleotide polymorphism (SNP) markers are being developed for molecular diagnosis of genetic disorders and large-scale population studies for genetic analysis of complex traits, a simple, sensitive, and specific test for single nucleotide changes is highly desirable. In this report we describe the development of a homogeneous DNA detection method that requires no further manipulations after the initial reaction is set up. This assay, named dye-labeled oligonucleotide ligation (DOL), combines the PCR and the oligonucleotide ligation reaction in a two-stage thermal cycling sequence with fluorescence resonance energy transfer (FRET) detection monitored in real time. Because FRET occurs only when the donor and acceptor dyes are in close proximity, one can infer the genotype or mutational status of a DNA sample by monitoring the specific ligation of dye-labeled oligonucleotide probes. We have successfully applied the DOL assay to genotype 10 SNPs or mutations. By designing the PCR primers and ligation probes in a consistent manner, multiple assays can be done under the same thermal cycling conditions. The standardized design and execution of the DOL assay means that it can be automated for high-throughput genotyping in large-scale population studies.

DNA Ligases↗

Novel genetic variations and haplotypes of hepatocyte nuclear factor 4alpha (HNF4A) found in Japanese type II diabetic patients.

Thirty-nine single nucleotide variations, including 16 novel ones, were found in the 5' promoter region, all of the exons and their surrounding introns of HNF4A in 74 Japanese type II diabetic patients. The following novel variations were identified (based on the amino acid numbering of splicing variant 2): -208G>C in the 5' promoter region; 1154C>T (A385V) and 1193T>C (M398T) in the coding exons; 1580G>A, 1852G>T, 2180C>T, 2190G>A, and 2362_2380delAAGAATGGTGTGGGAGAGG in the 3'-untranslated region, and IVS1+231G>A, IVS2-83C>T, IVS3+50C>T, IVS3-54delC, IVS5+173_176delTTAG, IVS5-181_-180delAT, IVS8-106A>G, and IVS9-151A>C in the introns. The allele frequencies were 0.311 for 2362_2380delAAGAATGGTGTGGGAGAGG, 0.054 for 1580G>A, 0.047 for 1852G>T, 0.020 for IVS1+231G>A, 0.014 for IVS9-151A>C, and 0.007 for the other 11 variations. In addition, one known nonsynonymous single nucleotide polymorphism, 416C>T (T139I), was detected at a 0.007 frequency. Based on the linkage disequilibrium profiles, the region analyzed was divided into three blocks. Haplotype analysis determined/inferred 10, 16, and 12 haplotypes for block 1, 2, and 3, respectively. Our results on HNF4A variations and haplotypes would be useful for pharmacogenetic studies in Japanese.

Asian People↗

Genetic variations of the AHR gene encoding aryl hydrocarbon receptor in a Japanese population.

Aryl hydrocarbon receptor (AhR), encoded by the AHR gene, is a transcriptional factor that induces various drug metabolizing enzymes in response to diverse endogenous and exogenous ligands. In order to identify genetic variations of the AHR gene, genomic DNA from 242 Japanese individuals was sequenced. We identified 32 single nucleotide variations, including 25 novel ones [7 were in the coding exons, 7 in the introns, 1 in the 5'-untranslated region (UTR), 5 in the 3'-UTR, 2 in the 5'-flanking region, and 3 in the 3'-flanking region] and a GGGGC repeat polymorphism (a novel microsatellite marker) in the promoter region. The novel nonsynonymous variations were 50A>C (Lys17Thr), 1202A>G (Lys401Arg), 1459A>G (Asn487Asp), and 1541T>C (Ile514Thr). The allele frequencies were 0.010 for 1459A>G (Asn487Asp) and 0.002 for the other 3 variations. Also detected in this analysis was the known nonsynonymous single nucleotide polymorphism 1661G>A (Arg554Lys) at a 0.444 frequency.

Asian People↗

Is a mutator analogous to the Ig hypermutator of the sheep ileal Peyer's patch active on MHC class I genes in the germ line?

Polymorphic sequence variation in the peptide-binding domains of MHC class I molecules appears to have been driven largely by the constructive action of natural selection on the specificity of the peptide-binding groove. Similar features are displayed by the variable domains of immunoglobulins generated in the sheep ileal Peyer's patch, but in this case there is evidence that the action of a targeted hypermutator acting on a selected substrate rather than antigen-driven selection is responsible for the pattern of variation in the system. Such a hypermutator acting in the germ line would not only mimic the action of natural selection but also, by convergent mutation, generate similar patterns of variation in unrelated alleles that could be interpreted as evidence for short-tract gene conversion. We analyzed human class I MHC alleles in the light of these data, but failed to find evidence of the action of a similar hypermutator. A search for other mutationally driven patterns of variation also failed, even in hypervariable residues from parsimonious phylogenies. Single-nucleotide variation at these residues is also frequent in recent allelic variants, but the data are as consistent with short-tract gene conversion as with base mutation. We conclude that the patterns of allelic variation in MHC molecules are not driven by mutational pressure, but rather by conventional mutational processes, accompanied by short-tract gene conversion and intense natural selection.

Alleles↗

Nucleotide sequence variations within the lipopolysaccharide biosynthesis gene gseA (Kdo transferase) among the Chlamydia trachomatis serovars.

The gene gseA, involved in the expression of the genus-specific epitope of chlamydial lipopolysaccharide (LPS), was analyzed by temperature gradient gel electrophoresis (TGGE) to visualize nucleotide sequence variations among the 15 serovars of Chlamydia trachomatis. Sequence analysis showed that the TGGE melting-profile patterns were able to detect single nucleotide variations within gseA and allowed the arrangement of the serovars in groups of both identical nucleotide sequences and sequences containing identical sites of nucleotide substitutions. Compared to serovar L2, four types of patterns were obtained: (i) serotypes A and Ba; (ii) B and C (causing endemic trachoma); (iii) D through K (causing sexually transmitted oculo-genital infections); (iv) L1 through L3 (the causative agents of lymphogranuloma venereum). A total of 58 isolated of C. trachomatis of genital or conjunctival origin were tested by this method in comparison to reference strains. Forty-eight isolates (13 of type E, 16 of type F, nine of type G, and ten of type K) yielded the same melting profile as the corresponding type strain, independent of whether they were isolated from genital or ocular infections. However, ten B serotype strains of genital origin behaved in TGGE like a typical genital strain and not a trachoma strain. Thus, although gseA was found to be highly conserved among C. trachomatis, the obtained TGGE profiles of the tested strains tended to correlate with their specific site of infection.

Amino Acid Sequence↗

Gene and protein domain-specific patterns of genetic variability within the G-protein coupled receptor superfamily.

INTRODUCTION: Guanine nucleotide binding proteins (G-proteins) represent the targets for >50% of all therapeutics. There is substantial interindividual variation in response to agonists and antagonists directed to these receptors, which may, in part, be due to genetic polymorphisms. As a class, the sequence variability of G-protein-coupled receptor (GPCR) genes has not been characterized. STUDY DESIGN: This variability was investigated by sequencing promoter, 5'- and 3'-UTR, coding blocks, and intron-exon boundaries, of 64 GPCR genes in an ethnically diverse group of 82 individuals. RESULTS: Of the 675 single-nucleotide variations found, 61% occurred in > or =1% of the population sample and the nature of these 412 single nucleotide polymorphisms (SNPs) was assessed. 5'-UTR (p = 0.002) and coding (p = 0.006) SNPs were observed more often in GPCR genes, compared with 309 non-GPCR genes similarly interrogated. The prevalence of non-synonymous coding SNPs was unexpectedly high, with 65% of GPCR genes having at least one. Intron-containing genes had half as many non-synonymous coding SNPs compared with intronless genes (p = 0.0009), suggesting that when introns are not available coding regions provide sites for variation. A distinct relationship between the prevalence of non-synonymous SNPs and receptor structural domains was evident (p = 0.0006 by ANOVA), with variability being most prominent in the transmembrane spanning domains (38%) and the intracellular loops (24%). Phosphoregulatory domains, particularly the carboxy terminus, often the site for agonist-promoted phosphorylation by G-protein coupled receptor kinases, were the least polymorphic (8%). CONCLUSIONS: There is substantial genetic variability in potentially pharmacologically relevant coding and noncoding regions of GPCRs. Such variability should be considered in the development of new agents, or optimization of existing agents, targeted to these receptors.

Analysis of Variance↗

Parallel gene analysis with allele-specific padlock probes and tag microarrays.

Parallel, highly specific analysis methods are required to take advantage of the extensive information about DNA sequence variation and of expressed sequences. We present a scalable laboratory technique suitable to analyze numerous target sequences in multiplexed assays. Sets of padlock probes were applied to analyze single nucleotide variation directly in total genomic DNA or cDNA for parallel genotyping or gene expression analysis. All reacted probes were then co-amplified and identified by hybridization to a standard tag oligonucleotide array. The technique was illustrated by analyzing normal and pathogenic variation within the Wilson disease-related ATP7B gene, both at the level of DNA and RNA, using allele-specific padlock probes.

Adenosine Triphosphatases↗

SYBR green-based real-time quantitative PCR assay for detection of West Nile Virus circumvents false-negative results due to strain variability.

Real-time quantitative PCR is used routinely for the high-throughput diagnosis of viral pathogens, such as West Nile virus (WNV). Rapidly evolving RNA viruses present a challenge for diagnosis because they accumulate mutations that may render them undetectable. To explore the effect of sequence variations on assay performance, we generated every possible single point mutation within the target region of the widely used TaqMan assay for WNV and found that the TaqMan assay failed to detect 47% of possible single nucleotide variations in the probe-binding site and was unable to detect any targets with more than two mutations. In response, we developed and validated a less expensive assay with the intercalating dye SYBR green. The SYBR green-based assay was as sensitive as the TaqMan assay for WNV. Importantly, it detected 100% of possible WNV target region variants. The assay developed here adds an additional layer of protection to guard against false-negative results that result from natural variations or drug-directed selection and provides a rapid means to identify such variants for subsequent detailed analysis.

Animals↗