Abstract
This protocol details the steps for data quality assessment and control that are typically carried out during case-control association studies. The steps described involve the identification and removal of DNA samples and markers that introduce bias. These critical steps are paramount to the success of a case-control study and are necessary before statistically testing for association. We describe how to use PLINK, a tool for handling SNP data, to perform assessments of failure rate per individual and per SNP and to assess the degree of relatedness between individuals. We also detail other quality-control procedures, including the use of SMARTPCA software for the identification of ancestral outliers. These platforms were selected because they are user-friendly, widely used and computationally efficient. Steps needed to detect and establish a disease association using case-control data are not discussed here. Issues concerning study design and marker selection in case-control studies have been discussed in our earlier protocols. This protocol, which is routinely used in our labs, should take approximately 8 h to complete.
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Acknowledgements
C.A.A. was funded by the Wellcome Trust (WT91745/Z/10/Z). A.P.M. was supported by a Wellcome Trust Senior Research Fellowship. K.T.Z. was supported by a Wellcome Trust Research Career Development Fellowship.
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C.A.A. wrote the first draft of the article. C.A.A. wrote scripts and performed analyses. C.A.A., F.H.P., G.M.C., A.P.M. and K.T.Z. revised the article. C.A.A., L.R.C., A.P.M. and K.T.Z. designed the protocol.
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The authors declare no competing financial interests.
Supplementary information
Supplementary Data
Simulated dataset for use with the protocol, contains the following files: hapmap3r2_CEU.CHB.JPT.YRI.founders.no-at-cg-snps.bed hapmap3r2_CEU.CHB.JPT.YRI.founders.no-at-cg-snps.bim 8813 2010-03-09 11:12 hapmap3r2_CEU.CHB.JPT.YRI.founders.no-at-cg-snps.fam hapmap3r2_CEU.CHB.JPT.YRI.no-at-cg-snps.txt high-LD-regions.txt imiss-vs-het.Rscript pca-populations.txt plot-IBD.Rscript plot-pca-results.Rscript raw-GWA-data.map raw-GWA-data.ped (file size ~2.5GB uncompressed) raw-GWA-data.prune.in run-diffmiss-qc.pl run-IBD-QC.pl (ZIP 451047 kb)
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Anderson, C., Pettersson, F., Clarke, G. et al. Data quality control in genetic case-control association studies. Nat Protoc 5, 1564–1573 (2010). https://doi.org/10.1038/nprot.2010.116
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DOI: https://doi.org/10.1038/nprot.2010.116
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