Questions tagged [gwas]

Questions pertaining to genome-wide association studies.

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How can SNP arrays be used to detect deletions within a gene?

I am reading a journal paper where the researchers are studying the effect of disease-causing mutations in the IL1RAPL1 gene. In the first figure of this paper, they show pedigrees of families where ...
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Phenotype-to-genotype mapping

My understanding is that GWAS or QTL attemp to extract potential SNP candidates responsible of a particular trait. However, is there any framework that attempts to do the opposite? This is, link the ...
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How many people need to have the same mutation of a gene in order for that gene to be seen as a feasible candidate for a disease?

I am learning about genome-wide association studies (GWAS) and I know that they are used to see whether certain SNPs are associated with a disease of interest. From everything that I have watched and ...
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Genome-wide association study (GWAS) search engine?

I am not a biologist and came across the term genome-wide association study or 'GWAS' for the first time today. Now I would like to see if there is a GWAS on the particular condition I am interested ...
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1 answer
51 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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2 votes
1 answer
44 views

Quantifying the Genetic Basis of Complex Diseases

In general, there are 2 types of diseases for which we understand "causality" very well: Infectious disease, where there is some etiological agent that causes the disease and Monogenic genetic ...
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1 answer
128 views

What does the MAF/MinorAlleleCount mean?

I'm not sure why reporting the second most frequent allele is helpful? what is the Major allele?
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N value in a GWAS?

Just like the title says. I am reading about a GWAS but I don't know much about them. I understood most of it but I couldn't figure out what the "n" value was.
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2 votes
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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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106 views

Are microsatellites viable markers for GWAS?

I'm just reading some papers on genome-wide association studies and find that most of them use SNPs as a marker. I understand that they're the most polymorphic and thus the best for accurate ...
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1 vote
1 answer
53 views

How to set the phenotype in GWAS analysis?

In the GWAS analysis, my animal sample phenotype is whether an individual dies or survives. And I have every sample death time. How do I set the phenotype in GWAS analysis?
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1 answer
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GWAS: marker map based on old genome assembly - can I use the new assembly to look for SNP positions?

I have an old set of pig SNP data and the positions were mapped using v10.2 of the assembly. I submitted a GWAS paper for review, and the reviewer wants to know if any of the significant SNPs that ...
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How many samples to run an association study on B-Cell receptors

We are trying to find biomarkers on the B-Cell receptor VDJ regions. To do this we plan to run Single cell RNA-Seq (using the solution from 10x genomics https://www.10xgenomics.com/solutions/vdj/) to ...
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4 votes
1 answer
3k views

GWAS terminology "Tag" vs "Lead" vs "Index" SNP

I'm trying to get my head round the correct GWAS terminology. I keep seeing the terms like "tag", "lead" and "index" SNP to be used almost interchangeably and I would like to get a clarification from ...
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6 votes
1 answer
426 views

Recommendations for textbooks on statistical and quantitative genetics, and genetic epidemiology

I'm looking for a textbook on statistical genetics, quantitative genetics, association mapping, and genetic epidemiology. My interests include, but are not limited to, complex trait analysis, and the ...
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337 views

What is a proper software to do GWAS analysis of tuberculosiis VCFs and phenotype data?

What is a proper software to do GWAS analysis of tuberculosis VCFs and phenotype data? Need a software which will accept VCF file and phenotype data as an input and produce genome wide association ...
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2 answers
72 views

same SNP rs# referenced to be found in two different genes

Two GWAS papers have referenced the same SNP (rs7442295), but one states it's found in the gene GLUT9 and the other states it's found in SCL2A9. The ncbi dbSNP says it's in SCL2A9, and I thought that ...
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Replication cohorts in microbial GWAS

Replication in an independent cohort is of course the gold standard in GWAS studies, and many high profile journals will now (quite rightly) not accept finding indicating a phenotype genotype ...
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1 vote
2 answers
95 views

Difference between imputing and typing in GWAS studies?

In genome-wide association studies (GWAS), what is the difference between imputing and typing? Are they the same?
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1 vote
1 answer
268 views

Why are Mendelian mutations considered rare?

I was reading the Wikipedia articles about genome-wide association studies (GWAS) and whole exome sequencing. As I understand, GWAS is used to identify most common SNPs that are proved to be ...
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3 votes
1 answer
475 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. ...
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5 votes
1 answer
252 views

Linkage Disequilibrium in GWAS

I see a lot of studies on GWAS not filter out for linkage disequilibrium or even make the slightest mention of it. Why is this the case? I would imagine that you want to keep SNPs that are only in ...
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7 votes
2 answers
4k views

GWAS: why is replication in another cohort so crucial?

Almost all the landmark GWAS (Genome-Wide Association Studies) reviews agree that, for a GWAS finding to be valid, it needs to be replicated in an independent cohort. What exactly is the rationale ...
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0 votes
2 answers
823 views

How to do whole genome sequence alignment in R or Ruby/C++, any good language? [closed]

I need to perform tuberculosis mutation analysis. First step I need to do is to align sequences in fasta format against one reference file. i tried CLC genomics workstation --- it hangs on 60 000 ...
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0 votes
1 answer
151 views

How to do a whole genome analysis of Multidrug-resistant Mycobacterium tuberculosis

I'm looking for tutorials and software that can help me study whole genome sequence data is and genome wide associations. I have Matlab and Bioconductor R so anything involving those packages would be ...
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90 views

Phenotype choice for one of a MZ twin pair in a genetic association study

I was having a discussion with a colleague and this question came up... It is commonplace in molecular genetics studies to only genotype one of a pair of monozygotic twins (and then implicitly impute ...
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1 vote
1 answer
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A question on exclusion of study participants for an Exome genotyping array

I'm reading a paper that used whole exome sequencing on an African American and European populations to discover novel low frequency and rare variants associated with lipid levels & the risk of ...
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1 vote
1 answer
57 views

Investigating rare variants in ethnically different populations (European ancestry & African ancestry)

If you are investigating low-frequency and rare variants for a complex trait using exome sequencing, why would one consider using different populations (African ancestry and European ancestry) ...
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3 votes
1 answer
811 views

GWAS: matched-pairs and logistic regression

Logistic regression is a common analysis tool used for GWAS when your response variable of interested is qualitative. It comes as one of the standard tools in most GWAS packages (e.g. PLINK). Most ...
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1 vote
1 answer
197 views

Interpreting SNP-in-gene associations from GWAS studies

For most SNPs identified in GWAS studies, is the underlying assumption that if it is indeed associated with a phenotype (and lets assume its associated because it affects protein function), that you ...
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11 votes
2 answers
6k views

What is the difference between naive and adjusted p-values in a GWAS study?

What is the difference between a naive p-value and an adjusted p-value in the results of a GWAS study? See from this paper: After Bonferroni adjustment, a single gene, DCTN4 (encoding dynactin 4) ...
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14 votes
1 answer
286 views

Paralogous genes in genome-wide association studies?

Has anybody tested if paralogous genes are over-represented among the genes identified by genome-wide association studies (GWAS)? For example, if a GWAS study finds 200 genes associated to the ...
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2 votes
1 answer
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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6 votes
2 answers
380 views

What is the relative power of GWAS studies in different species?

I would like to know of any publication studying the relative power of GWAS studies in different species. For example, I've seen reports that say genotyping and GWAS in dog breeds is much more ...
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