Combining inhouse data with 1000 genome for PCA
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6.4 years ago
ankita ▴ 20

For PCA analysis, I have common coordinates between Inhouse exome data and 1000 Genomes data (Phase 1). I want to retrieve genotypes for those common SNPs from VCF files in 1000 genomes [then convert to plink for smartPCA). I thought of a option of  converting all VCF files in phase 1 to ped which is very memory intensive. What can be the possible solution for this problem  ?

1000 Genome VCF file Forum • 4.1k views
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thanks, i will try this :)

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Consider using the 1000Genomes data for imputing the genotype of the SNPs missing in your dataset: http://www.1000genomes.org/faq/can-i-use-1000-genomes-data-imputation

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6.4 years ago

PLINK 1.9 supports direct conversion of VCF to .bed+.bim+.fam , which should be readable by smartpca.  For example,

plink --vcf ALL.chr1.phase1_release_v3.20101123.snps_indels_svs.genotypes.vcf.gz --out 1000g_chr1

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6.4 years ago
ankita ▴ 20

Hi

I am using vcf-concat to combine all VCF files from 1000 Genomes and then using plink 1.9. Is vcf-concat option is the only way for concatenation, is there any other way in plink 1.9 because it is much faster ?

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You can use plink --merge-list.

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6.4 years ago
ankita ▴ 20

I have used --merge-list but it throws an error and warnings for snp inconsistencies. What i understand is merging is used when  2 files have same snps and you have to merge data for different individuals with same snps while I want just want to concatenate two vcf files from different chromosomes say chr1 and chr2 for making one single plink file, in short i want to concatenate all vcf files of 1000 g to make one plink file.

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bcftools concat may be your best bet.  (--merge-list also handles concatenation, but each variant needs to have a unique ID.)

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