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Mean chi^2 of SNPs used to estimate Omega is low for some SNPsMTAG may not perform well in this situation. #221

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luciaC-C opened this issue Oct 20, 2024 · 1 comment

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@luciaC-C
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Hello,

First, thanks for amazing project and issue resolution.

I'm wondering if the message "Mean chi^2 of SNPs used to estimate Omega is low for some SNPsMTAG may not perform well in this situation" indicates a problem when using MTAG if the rest of the output looks reasonable.

Thank you!

2024/10/15/09:50:46 AM
<><><<>><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
<>
<> MTAG: Multi-trait Analysis of GWAS
<> Version: 1.0.8
<> (C) 2017 Omeed Maghzian, Raymond Walters, and Patrick Turley
<> Harvard University Department of Economics / Broad Institute of MIT and Harvard
<> GNU General Public License v3
<><><<>><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
<> Note: It is recommended to run your own QC on the input before using this program.
<> Software-related correspondence: [email protected]
<> All other correspondence: [email protected]
<><><<>><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>

Calling ./mtag.py
--n-name Neff
--sumstats trait1,trait2
--cores 5
--out

2024/10/15/09:50:46 AM Beginning MTAG analysis...
2024/10/15/09:50:46 AM MTAG will use the Z column for analyses.
2024/10/15/09:50:53 AM Read in Trait 1 summary statistics (6010326 SNPs) from trait1 ...
2024/10/15/09:50:53 AM <><><<>><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
2024/10/15/09:50:53 AM Munging Trait 1 <><><<>><><><><><><><><><><><><><><><><><><><><><><><><><><
2024/10/15/09:50:53 AM <><><<>><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
2024/10/15/09:50:53 AM Interpreting column names as follows:
2024/10/15/09:50:53 AM snpid: Variant ID (e.g., rs number)
n: Sample size
a1: a1, interpreted as ref allele for signed sumstat.
pval: p-Value
a2: a2, interpreted as non-ref allele for signed sumstat.
z: Directional summary statistic as specified by --signed-sumstats.

2024/10/15/09:50:53 AM Reading sumstats from provided DataFrame into memory 10000000 SNPs at a time.
2024/10/15/09:51:00 AM Read 6010326 SNPs from --sumstats file.
Removed 0 SNPs with missing values.
Removed 0 SNPs with INFO <= None.
Removed 0 SNPs with MAF <= 0.01.
Removed 0 SNPs with SE <0 or NaN values.
Removed 0 SNPs with out-of-bounds p-values.
Removed 0 variants that were not SNPs. Note: strand ambiguous SNPs were not dropped.
6010326 SNPs remain.
2024/10/15/09:51:03 AM Removed 0 SNPs with duplicated rs numbers (6010326 SNPs remain).
2024/10/15/09:51:03 AM Removed 331211 SNPs with N < 20523.3333333 (5679115 SNPs remain).
2024/10/15/09:51:55 AM Median value of SIGNED_SUMSTAT was 0.0, which seems sensible.
2024/10/15/09:51:55 AM Dropping snps with null values
2024/10/15/09:51:55 AM
Metadata:
2024/10/15/09:51:56 AM Mean chi^2 = 1.102
2024/10/15/09:51:56 AM Lambda GC = 1.097
2024/10/15/09:51:56 AM Max chi^2 = 29.371
2024/10/15/09:51:56 AM 1 Genome-wide significant SNPs (some may have been removed by filtering).
2024/10/15/09:51:56 AM
Conversion finished at Tue Oct 15 09:51:56 2024
2024/10/15/09:51:56 AM Total time elapsed: 1.0m:3.43s
2024/10/15/09:52:03 AM <><><<>><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
2024/10/15/09:52:03 AM Munging of Trait 1 complete. SNPs remaining: 5679115
2024/10/15/09:52:03 AM <><><<>><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>

2024/10/15/09:52:18 AM Read in Trait 2 summary statistics (5915125 SNPs) from trait2 ...
2024/10/15/09:52:18 AM <><><<>><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
2024/10/15/09:52:18 AM Munging Trait 2 <><><<>><><><><><><><><><><><><><><><><><><><><><><><><><><
2024/10/15/09:52:18 AM <><><<>><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
2024/10/15/09:52:18 AM Interpreting column names as follows:
2024/10/15/09:52:18 AM Neff: Sample size
a1: a1, interpreted as ref allele for signed sumstat.
pval: p-Value
a2: a2, interpreted as non-ref allele for signed sumstat.
snpid: Variant ID (e.g., rs number)
z: Directional summary statistic as specified by --signed-sumstats.

2024/10/15/09:52:18 AM Reading sumstats from provided DataFrame into memory 10000000 SNPs at a time.
2024/10/15/09:52:24 AM Read 5915125 SNPs from --sumstats file.
Removed 0 SNPs with missing values.
Removed 0 SNPs with INFO <= None.
Removed 0 SNPs with MAF <= 0.01.
Removed 0 SNPs with SE <0 or NaN values.
Removed 0 SNPs with out-of-bounds p-values.
Removed 0 variants that were not SNPs. Note: strand ambiguous SNPs were not dropped.
5915125 SNPs remain.
2024/10/15/09:52:27 AM Removed 0 SNPs with duplicated rs numbers (5915125 SNPs remain).
2024/10/15/09:52:28 AM Removed 0 SNPs with N < 28823.0 (5915125 SNPs remain).
2024/10/15/09:53:22 AM Median value of SIGNED_SUMSTAT was -0.0769731, which seems sensible.
2024/10/15/09:53:22 AM Dropping snps with null values
2024/10/15/09:53:22 AM
Metadata:
2024/10/15/09:53:23 AM Mean chi^2 = 1.257
2024/10/15/09:53:23 AM Lambda GC = 1.216
2024/10/15/09:53:23 AM Max chi^2 = 38.418
2024/10/15/09:53:23 AM 128 Genome-wide significant SNPs (some may have been removed by filtering).
2024/10/15/09:53:23 AM
Conversion finished at Tue Oct 15 09:53:23 2024
2024/10/15/09:53:23 AM Total time elapsed: 1.0m:5.2s
2024/10/15/09:53:30 AM <><><<>><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
2024/10/15/09:53:30 AM Munging of Trait 2 complete. SNPs remaining: 5915125
2024/10/15/09:53:30 AM <><><<>><><><><><><><><><><><><><><><><><><><><><><><><><><><>

2024/10/15/09:53:41 AM Dropped 842325 SNPs due to strand ambiguity, 4836790 SNPs remain in intersection after merging trait1
2024/10/15/09:53:51 AM Flipped the signs of of 2187326 SNPs to make them consistent with the effect allele orderings of the first trait.
2024/10/15/09:53:53 AM Dropped 0 SNPs due to strand ambiguity, 4024959 SNPs remain in intersection after merging trait2
2024/10/15/09:53:53 AM ... Merge of GWAS summary statistics complete. Number of SNPs: 4024959
2024/10/15/09:54:01 AM Using 4024959 SNPs to estimate Omega (0 SNPs excluded due to strand ambiguity)
2024/10/15/09:54:01 AM Estimating sigma..
2024/10/15/09:54:38 AM Checking for positive definiteness ..
2024/10/15/09:54:38 AM Sigma hat:
[[1.084 0.003]
[0.003 1.031]]
2024/10/15/09:54:38 AM Mean chi^2 of SNPs used to estimate Omega is low for some SNPsMTAG may not perform well in this situation.
2024/10/15/09:54:38 AM Beginning estimation of Omega ...
2024/10/15/09:54:38 AM Using GMM estimator of Omega ..
2024/10/15/09:54:39 AM Checking for positive definiteness ..
2024/10/15/09:54:39 AM matrix is not positive definite, performing adjustment..
2024/10/15/09:54:39 AM Completed in 0 iterations
2024/10/15/09:54:39 AM Completed estimation of Omega ...
2024/10/15/09:54:39 AM Beginning MTAG calculations...
2024/10/15/09:54:58 AM ... Completed MTAG calculations.
2024/10/15/09:54:58 AM Writing Phenotype 1 to file ...
2024/10/15/09:55:23 AM Writing Phenotype 2 to file ...
2024/10/15/09:55:48 AM
Summary of MTAG results:

Trait # SNPs used ... MTAG mean chi^2 GWAS equiv. (max) N
1 ...trait1 4024959 ... 1.268 476858
2 ...trait2 4024959 ... 1.273 48210

[2 rows x 7 columns]

Estimated Omega:
[[6.135e-07 1.895e-06]
[1.895e-06 5.970e-06]]

(Correlation):
[[1. 0.99]
[0.99 1. ]]

Estimated Sigma:
[[1.084 0.003]
[0.003 1.031]]

(Correlation):
[[1. 0.002]
[0.002 1. ]]

MTAG weight factors: (average across SNPs)
[0.369 1.138]

2024/10/15/09:55:48 AM
2024/10/15/09:55:48 AM MTAG results saved to file.
2024/10/15/09:55:48 AM MTAG complete. Time elapsed: 5.0m:2.1940908432s

@paturley
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paturley commented Oct 21, 2024 via email

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