<blockquote>
<p>Is 1kg.v3.tgz based on GRCh37?</p>
</blockquote>
<blockquote>
<p>Is there a GRCh38 reference version of 1000 genomes that is split to different super populations (EUR etc)?</p>
</blockquote>
<p>Yes, the genome build for 1000 Genomes phase 3 release is in GRCh37. Luckily ISGR has reanalyzed their original sequencing data based on GRCh38. The data is provided both at the ISGR website <a href="https://www.internationalgenome.org/data-portal/data-collection/30x-grch38" rel="nofollow noreferrer">https://www.internationalgenome.org/data-portal/data-collection/30x-grch38</a> and it is also made available by Christopher at PLINK2 website <a href="https://www.cog-genomics.org/plink/2.0/resources" rel="nofollow noreferrer">https://www.cog-genomics.org/plink/2.0/resources</a>. However I suspect the data was not split into super populations.</p>
<blockquote>
<p>Can you use GRCh37 based reference to LD clump GRCh38 GWAS results?</p>
</blockquote>
<p>I wouldn't recommend doing so. Some variants identified in GRCh37 has been merged into others in GRCh38. Some variants are assigned different rsIDs. The position for the variant may also differ in different genome builds. Therefore clumping GRCh38 GWAS results with GRCh37 based reference may lead to fewer variants correctly mapped, which may influence your furthur analysis.</p>
<p>Hope you find it helpful. Best regards.</p>

CC BY-SA 4.0
2023-10-20T18:49:17.073Z
2023-10-20T18:49:17.073Z
Lloyd_LiuSiyi
<p>The vignette of R package <code>ieugwasr</code> describes a <code>plink</code> based wrapper function for LD clumping GWAS data using the <em>1000 genomes reference dataset</em> (<a href="http://fileserve.mrcieu.ac.uk/ld/1kg.v3.tgz" rel="nofollow noreferrer">http://fileserve.mrcieu.ac.uk/ld/1kg.v3.tgz</a>). I would like LD clump GRCh38 based GWAS data. I am under the impression that the previous LD reference dataset is based on GRCh37. Therefore, I kindly ask:</p>
<ul>
<li>Is <code>1kg.v3.tgz</code> based on GRCh37?</li>
<li>Can you use GRCh37 based reference to LD clump GRCh38 GWAS results?</li>
<li>Is there a GRCh38 reference version of 1000 genomes that is split to different super populations (EUR etc)?</li>
</ul>

<gwas><reference-genome><1000genomes><ld>
LD clump GRCh38 GWAS results
# LD clump GRCh38 GWAS results

(Asked by: username_0 on 2023-06-30)

The vignette of R package `ieugwasr` describes a `plink` based wrapper function for LD clumping GWAS data using the *1000 genomes reference dataset* (<http://fileserve.mrcieu.ac.uk/ld/1kg.v3.tgz>). I would like LD clump GRCh38 based GWAS data. I am under the impression that the previous LD reference dataset is based on GRCh37. Therefore, I kindly ask:

* Is `1kg.v3.tgz` based on GRCh37?
* Can you use GRCh37 based reference to LD clump GRCh38 GWAS results?
* Is there a GRCh38 reference version of 1000 genomes that is split to different super populations (EUR etc)?

**Tags:** gwas, reference-genome, 1000genomes, ld

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## 1 answers

### Answer by username_1 on 2023-10-20. Score: 2

> Is 1kg.v3.tgz based on GRCh37?

> Is there a GRCh38 reference version of 1000 genomes that is split to different super populations (EUR etc)?

Yes, the genome build for 1000 Genomes phase 3 release is in GRCh37. Luckily ISGR has reanalyzed their original sequencing data based on GRCh38. The data is provided both at the ISGR website <https://www.internationalgenome.org/data-portal/data-collection/30x-grch38> and it is also made available by Christopher at PLINK2 website <https://www.cog-genomics.org/plink/2.0/resources>. However I suspect the data was not split into super populations.

> Can you use GRCh37 based reference to LD clump GRCh38 GWAS results?

I wouldn't recommend doing so. Some variants identified in GRCh37 has been merged into others in GRCh38. Some variants are assigned different rsIDs. The position for the variant may also differ in different genome builds. Therefore clumping GRCh38 GWAS results with GRCh37 based reference may lead to fewer variants correctly mapped, which may influence your furthur analysis.

Hope you find it helpful. Best regards.


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