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Output of METAL meta-analysis: which allele does the beta refer to?

Hi,

I have run a meta-analysis using METAL, and I have an output file (ending in ".tbl") including an "Effect" column and an "Allele1" and "Allele2". I would like to compare the effect column of this analysis to another dataset, but in order to do so I need to align the betas depending on which allele the effects refer to. I was wondering if I can assume that the effect is computed for the allele specified in the "Allele1" field.

The Wiki documentation for METAL talks about the first study included in the meta-analysis being used as the reference for the alleles, so if I am understanding this correctly the "Effect" is expressed in reference to "Allele1". If this is not the case, how can I find the allele that is used as the effect allele?

Thank you very much for all your help,

Simone

metal meta-analysis

1 answer

METAL creates a .tbl.info file when running the analysis which describes the output. It states that the Effect column corresponds to the "overall estimated effect size for allele1".

Hi,

Can you please tell me how to include BETA and SE in the output of METAL?

When I just run:

./metal < metal.txt

I just get this columns:

head  METAANALYSIS1.TBL

MarkerName  Allele1 Allele2 Weight  Zscore  P-value Direction
rs2326918   a   g   19586.00    0.254   0.7991  --+
rs668796    c   g   19586.00    -2.064  0.03904 -+-

vi metal.txt

MARKER   SNP
DEFAULTWEIGHT   1211
ALLELE   A1 A2
EFFECT   BETA
STDERR   SE
PVAL     P

PROCESS EDIC.GWAS.reduce.txt

MARKER   SNP
ALLELE   A1 A2
DEFAULTWEIGHT   1363
EFFECT   BETA
STDERR   SE
PVAL     P

PROCESS GOKIND.GWAS.reduce.txt

OUTFILE EDIC_GOKIND_UKB_META.tbl
ANALYZE

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