Questions tagged [snp]

Single nucleotide polymorphisms, or SNPs, are differences between two sequences of DNA at one individual nucleotide location.

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1answer
994 views

Whole Genome Sequencing vs Whole Exome Sequencing

I am working on a project where I want to discover causative genes for a certain disease I may have. I was wondering whether to get WGS or WES to perform this experiment:- I am looking at SNP's and ...
7
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1answer
308 views

What about 23andMe's SNP test gives it such bad efficacy as a diagnostic tool?

The recent news about the FDA stopping the google backed 23andMe service selling any more kits got me thinking. I understand the company may have been selling it as a medical tool prematurely, but ...
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Effect of single nucleotide deletion or insertion on primer annealing

How is primer annealing, and, consequently, PCR amplification affected by single nucleotide deletion or insertion inside the primer ? Imagine a primer like this: GCGTCATAAAGGGGACGTG (primer) and ...
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1answer
6k views

What is the difference between Single Nucleotide Polymorphism (SNP), Mutation and Structural Variation(SV)?

This is a question which plagues many people and today I was wondering it myself while writing a grant. Indeed, I've seen many people use the terms interchangeably, but they are all very different ...
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1answer
10k views

Ancestral Allele explanation

I'm having some trouble understanding the concept of ancestral allele. What exactly does it mean? What does it have to do with Identity by descent/state? What does it have to do(if anything) with SNP'...
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4answers
257 views

Statistician confused about exact SNP data type

I'm from a statistical (not biological) background, and I'm very confused about what exactly is the "data" associated with a SNP. Below, I'll explain things as best I can--please correct me ...
5
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1answer
197 views

Location of TFBS in genome

I have an annotated set of SNPs and I would like to explore the difference in the binding affinity of the transcription factor (TF) if I have a SNP in my locus. As my SNPs are annotated (I know wether ...
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3answers
1k views

How do you merge SNP data with a reference genome?

My Data I have a 23andMe file listing SNPs in the form: ...
5
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1answer
102 views

What method would you use to genotype SNPs in low quality samples?

What method would you use to genotype SNPs in low quality samples? I ideally want to genotype hundreds of SNPs in hundreds of scat samples (very low amount of target DNA, potentially degraded and ...
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2answers
497 views

Trying to understand the big picture behind DNA sequencing, alignment and searching

I'm about to start a bioinformatics research project but I haven't any biological background. I know my project is in regards to a performance analysis of DNA sequencing and searching "weapons" like ...
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3answers
2k views

SNPs in the Human Genome

I read online that they have found around 10 million single nucleotide polymorphisms (SNPs) across individuals in the human genome [1]. However, this number includes all SNPs found in all people who ...
4
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2answers
324 views

SNPs in DNase hypersensitive and histone marks sites

I am investigating a role of SNPs in DNase hypersensitive sites and in the DNA regions of histone marks and have some questions about it. SNPs in DNase hypersensitive sites might mean that those SNPs ...
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3answers
251 views

Is there any source for raw data of SNP genotype frequency?

On sites like SNPedia, some pages contain the frequency of the SNP in question in different populations, based on published research. I'm trying to write a script that takes 23andme data and compares ...
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49 views

Relation between bases while changing into a SNP

Is there any relation or influence among the bases (A, C, G, T) while they are converted into a snp? Such as, is A converted ...
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3answers
210 views

Single copy housekeeping genes

I am working on a tool for SNP calling in polyploid plants. To test my method, I need a list of housekeeping genes common in almost all plants. For my case, these genes must be single copy (ie each HK ...
3
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1answer
170 views

Understanding these SNP annotations

I am looking at the PharmaPGKB database for SNPs and trying to understand what the following annotation means: rs1801131 at 1:11854475 in CLCN6, MTHFR (VIP) Ok, ...
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1answer
474 views

Why perform imputation?

Genetics datasets contain measurements for millions of single nucleotide polymorphisms (SNPs). Some (usually small) percentage of these values are of low confidence, and are labeled as missing values. ...
3
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3answers
314 views

Publicly available genotype data?

I am a statistician and I'd like to test my new method on biological data. For this I am looking for genotype data for a number of individuals. That is, I am looking for something like this: ...
3
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1answer
409 views

Regarding the NCBI FTP site

I am trying to extract information about SNP data from the FTP server of NCBI. Could someone please explain to me how the directory is organised? There are many many files and folders and I can't ...
3
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1answer
93 views

What is the genetic distance where linkage can be ignored?

I heard several times that two SNPs, that have at least 1'000 nucleotides between them, can be seen as 'unlinked' due to frequent recombination events. I also once saw a paper showing a graph "degree ...
3
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1answer
196 views

Figuring out if populations from two regions share the same Neanderthal haplotypes

I am going to preface this post in that I am not sure if it belongs here, but considering it has been ignored everywhere else I have tried I thought it is worth a shot. I am a graduate student who is ...
3
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1answer
171 views

Comparing SIFT and PolyPhen to other methods

I'm looking for a database of nsSNP (non synonymous single nucleotide polymorphisms) and their effects. As I understand, the common methods to predict this are SIFT and PolyPhen, and I want to compare ...
3
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1answer
251 views

Real-time PCR delay in Cq due to insertion SNP in primer

I am collecting evidence, even anecdotal, how does single nucleotide deletion or insertion in primer region affect the outcome of real-time PCR. I am most interested in how much there is a delay in ...
3
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2answers
230 views

Why only heterogeneous SNVs for validation using genotyping arrays?

I am trying to validate the variants I found using whole genome sequencing . The standard practice, I have seen in the two publications below were to check for the number of heterozygous SNPs called ...
3
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1answer
92 views

Genetic variation in humans and model organisms (measured by SNPs)

I was wondering what is the range of SNP density across species and model organisms. I.e., what would be a reasonable estimate for the SNP density (i.e., x SNPs for each 1 Kb) in: humans humans with ...
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1answer
4k views

What is pQTL and why do we need eQTL?

eQTLs are genomic loci that contribute to variation in expression levels of mRNAs (wikipedia). There is data out there that shows that ~60% of the time, the amount of mRNA in a cell is directly ...
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3answers
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Which side of the DNA helix is used for describing SNPs?

In genetic research I often come across references to single-nucleotide polymorphisms (SNPs). An example is rs3184504(C;T). As far as I understand it: In this ...
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1answer
5k views

Definition and example of Gene Variant

Could someone clearly define what a gene variant is with an example. I am totally confusing myself with SNPs, alleles, variants and how the major and minor allele are defined. An example with gene ...
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1answer
221 views

Are genes associated with obesity selected for?

I've read that there are several SNPs associated with increased risk of clinical or morbid obesity. I was wondering if there is any evidence that these are under positive selection. Would you expect ...
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1answer
52 views

DNA Analysis (AncestryDNA)

A recent1 AncestryDNA commercial highlights a customer who discovered that she was 26% Native American. Credit: ancestry.com/dna You can see the full commercial here. My question is, how can this ...
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1answer
3k views

Why is Sanger sequencing inferior for detecting SNPs in cancer cells?

I am familiar with Sanger sequencing, but at the level of an undergraduate. A lecturer of mine tried to describe Sanger sequencing as losing the sequence information in noise when used to detect ...
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1answer
80 views

variation in expression accounted for a SNP -- what's a usual percent?

I am reading a GWAS paper that found a SNP associated to predisposition to colon cancer and was assessed for gene expression of the nearby gene. They found that the genotype accounted for 55% of the ...
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2answers
98 views

identifying which SNPs sit in TFBS (Yeast)

i have a set of ~11k SNPs for Saccharomyces cerevisiae, baker's yeast and i would like to identify which ones of these sit in transcription factor binding sites and if they do information on the ...
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2answers
81 views

Database of medically validated SNPs

I'm looking for all possible sources of clinically tested human SNPs. There is a handful of databases that store SNPs (like dbSNP), but I only need those that have validated presence/absence of ...
2
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1answer
77 views

Where can I upload non-human Genotype data?

I have genotype data from few chicken population and I want to (need to) upload them somewhere online with free access. I have searched the web but I haven't found any place for non-human genotype ...
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0answers
88 views

What are the different types of SNPs?

When I search for this online I get answers such as substitutions, deletions, insertions etc. But I mean in the sense that I have been reading different terms infront of the word SNP such as: lead SNP,...
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0answers
392 views

what is the meaning of the genotype values in each snp

I understand that snp is a single base variation. For example, if person 1 has the sequence in DNA , AAGCCTA the second has AAGCTTA, then the allels are C,T. My question is what is the meaning of 0,...
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0answers
45 views

Calculate signifficance of SNP in specific trinucleotides [closed]

So, I have calculated the frequency of all SNPs (single nucleotide mutations) in some samples and have also found the nucleotides on the 3' and 5' sides of the mutated nucleotide. So I have a list of ...
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0answers
64 views

What is the best test for SNV clustering?

I am looking for a method to cluster single nucleotide polymorphisms based on clinicopathologic data (mainly receptor immunoistochemistry). So far, I've came up with only two that handle dummy ...
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2answers
52 views

Personal Genomic Data Samples

a quick question. I am looking for complete personal genomic data of human individuals. The only requirement for the genomic data is that it contains the complete set of SNPs of a human individual. So ...
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3answers
403 views

What fraction of sites are expected to be polymorphic?

Question Consider a very long (eventually infinite) DNA sequence of neutral sites. Consider a panmictic population of constant size $N$ with a per site mutation rate of $\mu$ where all individuals ...
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2answers
3k views

What is the difference between a fixed substitution and a single nucleotide polymorphism (SNP)?

I recently read a report that stated "We found 430 fixed substitutions […], with an additional 34 single nucleotide polymorphisms (SNPs) fixed within individual patients." What is the difference ...
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1answer
12k views

What is the difference between SNP and STR?

I thought that these were just different format of the same data. But it seems there isn't a way to convert SNP (single nucleotide polymorphism) data to STR (short tandem repeat) data. Am I right? ...
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1answer
47 views

What's the role of SNP (Single Nucleotide Polymorphism) in a disease when there is no gene associated to that SNP

I am quite new to the field of GWAS (genome-wide association studies), and I'm combining GWAS results and single cell analysis on type-1 diabetes (T1D), to see the role of cell specificity on the ...
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2answers
231 views

GEN file format, SNPs and alleles

I have a few questions I can't seem to get a straight answer to, regarding the .gen file format and also biology in general. The ...
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1answer
69 views

How do I interpret SNP nomenclature?

I am combing through my 23 & me raw data and I am a little confused on SNP terminology. I am using NCBI's genome browser and SNP database. As an example we can all follow here is a link to a ...
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1answer
30 views

Chromosome position mismatch for SNPs in dna tests

TL;DR: why is the position reported by DNA testing companies for an SNP on a particular chromosome different than the one in dbSNP/SNPedia databases? I'm analyzing the raw DNA exports for the same ...
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2answers
252 views

How to predict the effect of a non coding SNP variant on the expressed protein?

I am writing a paper for non coding SNPs on patients with metastatic breast cancer. Having used a specific gene panel (NGS) of approximately 60 genes, I'm currently running out of ideas on what to ...
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1answer
3k views

Why do almost all SNPs have two alleles?

Reading the Wikipedia page for SNPs I find the sentence "Almost all common SNPs have only two alleles." This is consistent with terminology elsewhere, such as the therm "Minor allele frequency", which ...
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1answer
162 views

Single Nucleotide Polymorphisms and diseases

I am writing a report on how Single Nucleotide Polymorphisms occurring in each of these regions: Transcription factor (TF) binding sites Epigentic signals Splicing variants MicroRNA binding sites ...