Two-Sample Mendelian Randomization

Two-Sample Mendelian Randomization is a skill for Claude Code, Codex from TianGzlab/OmicsClaw. It costs 7 tokens per session (2,778 once invoked), scanned A, original, Apache-2.0.

A workflow for two-sample Mendelian randomization, a genetic-statistics method that uses inherited variants to test whether one trait may causally affect another.

In plain words
What is it for?
Testing relationships between exposure and outcome traits with GWAS summary data, OpenGWAS identifiers, and optional outlier checks.
Why use it?
It helps examine causal direction when ordinary associations could be explained by confounding factors, using summary statistics from separate studies.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Testing relationships between exposure and outcome traits with GWAS summary data, OpenGWAS identifiers, and optional outlier checks.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/tiangzlab/omicsclaw/mendelian-randomization-twosamplemr
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add TianGzlab/OmicsClaw --skill mendelian-randomization-twosamplemr
Clone the repo
git clone --depth 1 https://github.com/TianGzlab/OmicsClaw

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for Two-Sample Mendelian Randomization

README.md
[![agentmods](https://agentmods.dev/badge/skills/tiangzlab/omicsclaw/mendelian-randomization-twosamplemr/github.svg)](https://agentmods.dev/skills/tiangzlab/omicsclaw/mendelian-randomization-twosamplemr)
Your own site
<a href="https://agentmods.dev/skills/tiangzlab/omicsclaw/mendelian-randomization-twosamplemr"><img src="https://agentmods.dev/badge/skills/tiangzlab/omicsclaw/mendelian-randomization-twosamplemr/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for Two-Sample Mendelian Randomization

Your own site · 80×15
<a href="https://agentmods.dev/skills/tiangzlab/omicsclaw/mendelian-randomization-twosamplemr"><img src="https://agentmods.dev/badge/skills/tiangzlab/omicsclaw/mendelian-randomization-twosamplemr.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 7 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,778 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00007 $0.02778
Opus 5 $0.00003 $0.01389
Sonnet 5 $0.00001 $0.00556
Haiku 4.5 $0.00001 $0.00278

Measured 9d ago against content hash 73d677477cc1, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

Two-Sample Mendelian Randomization scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

knowledge_base/mendelian-randomization-twosamplemr/SKILL.md · 216 lines

How it starts

The opening of the file, as written. The whole thing — 216 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Two-Sample Mendelian Randomization

When to Use This Skill

  • You have GWAS summary statistics for an exposure and outcome trait
  • You want to test causal direction between two traits (not just correlation)
  • You need to assess whether an observed association is likely causal or confounded
  • You want to use genetic variants as instrumental variables (natural experiment)
  • You have OpenGWAS trait IDs or your own GWAS summary statistics files

Not suitable for: One-sample MR (individual-level data), non-linear MR, multivariable MR with >2 exposures

Installation

install.packages(c("remotes", "ggplot2", "ggprism", "dplyr", "rmarkdown"))
remotes::install_github("MRCIEU/TwoSampleMR")
# For PDF report generation (optional but recommended):
# install.packages("tinytex"); tinytex::install_tinytex()
# For MR-PRESSO outlier detection (optional but recommended):
# remotes::install_github("rondolab/MR-PRESSO")
Software Version License Commercial Use
TwoSampleMR ≥0.5.6 GPL-3 ✅ Permitted
ieugwasr ≥0.2.1 MIT ✅ Permitted
ggplot2 ≥3.4.0 MIT ✅ Permitted
ggprism ≥1.0.3 GPL (≥3) ✅ Permitted
dplyr ≥1.1.0 MIT ✅ Permitted
rmarkdown ≥2.20 GPL-3 ✅ Permitted

Inputs

Option A — OpenGWAS IDs (recommended):

  • Exposure ID (e.g., "ieu-a-300" for LDL cholesterol)
  • Outcome ID (e.g., "ieu-a-7" for coronary heart disease)
  • Browse available traits at: https://gwas.mrcieu.ac.uk/

Option B — User-provided files (CSV/TSV):

  • Exposure GWAS summary statistics
  • Outcome GWAS summary statistics
Required Column Description Example
SNP rsID rs1234567
beta Effect estimate 0.05
se Standard error 0.01
pval P-value 5e-10
effect_allele Effect allele A
other_allele Other allele G
eaf Effect allele frequency (optional) 0.3

Outputs

Results (CSV):

  • mr_results.csv — MR estimates from all 4 methods (beta, SE, p-value, nSNP, F-statistics)
  • heterogeneity_results.csv — Cochran's Q test for instrument heterogeneity
  • pleiotropy_results.csv — MR-Egger intercept test for directional pleiotropy
  • directionality_results.csv — Steiger test confirming causal direction
  • harmonized_data.csv — SNP-level harmonized exposure-outcome data
  • single_snp_results.csv — Per-SNP Wald ratio estimates
  • leaveoneout_results.csv — Leave-one-out robustness estimates
  • MR-PRESSO outlier results (if heterogeneity significant and MRPRESSO installed)

Read the full file on GitHub · 216 lines

Files

What ships with it

7 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 9d ago First seen · 216 lines · 7 tokens per session scan A 73d677477cc1

Subscribe to this mod's changes

Two-Sample Mendelian Randomization is a skill published in the GitHub repository TianGzlab/OmicsClaw (160 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 7 tokens to every session and 2,778 once invoked, about $0.0000 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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