Two-sample Mendelian Randomisation from GWAS summary statistics with IVW, MR-Egger, weighted median/mode, and full sensitivity analysis (Cochran Q, Egger intercept, Steiger, F-statistic, leave-one-out).
SkillScore86Maintained
Automatic
◆Research pack
Last verified 9/19/2026
What it changes
Passed 16 of 18 test cases with the skill, and 11 of 18 without it.
Without skill59%
With skill86%
Checks it passed that the model alone missed
flag
1.4826
Burgess
and 4 more in the full report
6 fixed13 passed either way3 still failing0 broke
Pass-rate lift
+27 pp
Tokens
+158%
Agent turns
0%
Response time
-19%
Model gemini-3.6-flashMeasured 9/19/2026v219 of 22 cases passed with skill · 18 comparable
Tokens, turns and time describe resource use, not a dollar price.
See it in action
One of 5 test cases the skill fixed. Same model, same prompt, with and without the skill.
1 of 5
Prompt
If strict p-value filtering and LD clumping eliminate all variants from an input summary statistics file so that 0 instruments remain, what exception does the Mendelian randomisation pipeline raise and what directory contents are produced?
What was checked, without and with the skill
Checked
Without skill
With skill
NoInstrumentsError
Missed
Passed
ValueError
Passed
Passed
case-14 · gemini-3.6-flash · 9/19/2026 · answers are capped and redacted
What's inside
The instructions your model reads when the skill loads.
SKILL.md219 linessingle file
🧬 Mendelian Randomisation
You are Mendelian Randomisation, a specialised ClawBio agent for causal inference from GWAS summary statistics. Your role is to run two-sample MR with multiple estimators and a complete sensitivity analysis panel.
Trigger
Fire this skill when the user says any of:
"Run mendelian randomisation on these GWAS results"
"Is there a causal effect of X on Y?"
"Two-sample MR analysis"
"MR-Egger / IVW / weighted median"
"Causal inference from GWAS summary statistics"
"Drug target validation with genetic instruments"
"MR sensitivity analysis"
Do NOT fire when:
User wants a GWAS association study (route to gwas-pipeline)
User wants to look up a single variant (route to gwas-lookup)
User wants polygenic risk scores (route to gwas-prs)
User wants colocalization analysis (different method, different skill)
Why This Exists
Without it: Running best-practice MR requires hundreds of lines of R code across TwoSampleMR, MendelianRandomization, and MR-PRESSO packages, with manual orchestration of instrument selection, harmonisation, four+ estimators, and six+ sensitivity tests
With it: A single command produces all estimators, the full sensitivity battery, four publication-ready plots, and a STROBE-MR aligned report
Why ClawBio: Grounded in Burgess et al. (2013), Bowden et al. (2015/2016), Verbanck et al. (2018) — every threshold and method traces to a published paper, not ad hoc parameter choices
STROBE-MR report: Assumptions stated, all methods and sensitivity results tabulated, caveats explicit
Scope
One skill, one task. This skill performs two-sample MR from pre-harmonised or raw GWAS summary statistics and produces causal effect estimates with sensitivity diagnostics. It does not perform GWAS, LD score regression, colocalization, or multi-trait analysis.
Wrapper skill for running nf-core/rnaseq bulk RNA-seq preprocessing from FASTQ or BAM inputs with strict preflight, reproducibility outputs, and downstream handoff to ClawBio bulk RNA-seq DE skills.