

# Two sample MR report

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## SPG21_Macrophages against UKB-b-18436

Date: **13 January, 2026**

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### Results from two sample MR:


|method                    | nsnp|          b|        se|      pval|
|:-------------------------|----:|----------:|---------:|---------:|
|MR Egger                  |    4| -0.1066471| 0.3366914| 0.7814387|
|Weighted median           |    4|  0.0526006| 0.0227663| 0.0208628|
|Inverse variance weighted |    4|  0.0572779| 0.0192089| 0.0028652|
|Simple mode               |    4|  0.0499171| 0.0280059| 0.1727043|
|Weighted mode             |    4|  0.0497902| 0.0312078| 0.2088833|

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### Heterogeneity tests


|method                    |         Q| Q_df|    Q_pval|
|:-------------------------|---------:|----:|---------:|
|MR Egger                  | 0.1171949|    2| 0.9430863|
|Inverse variance weighted | 0.3550116|    3| 0.9493709|

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### Test for directional horizontal pleiotropy


| egger_intercept|        se|      pval|
|---------------:|---------:|---------:|
|        0.050502| 0.1035589| 0.6740065|

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### Test that the exposure is upstream of the outcome


| snp_r2.exposure| snp_r2.outcome|correct_causal_direction | steiger_pval|
|---------------:|--------------:|:------------------------|------------:|
|        3.63e-05|              0|TRUE                     |    0.5693824|

Note - R^2 values are approximate

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### Forest plot of single SNP MR

![plot of chunk chunk5](figure/SPG21Macrophages_against_UKBb18436chunk5-1.png)

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### Comparison of results using different MR methods

![plot of chunk chunk6](figure/SPG21Macrophages_against_UKBb18436chunk6-1.png)

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### Funnel plot

![plot of chunk chunk7](figure/SPG21Macrophages_against_UKBb18436chunk7-1.png)

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### Leave-one-out sensitivity analysis

![plot of chunk chunk8](figure/SPG21Macrophages_against_UKBb18436chunk8-1.png)
