$npx -y skills add GPTomics/bioSkills --skill proteome-mr-drug-targetRuns cis-pQTL Mendelian randomization for drug-target validation using UKB-PPP (Olink), deCODE (SomaScan), Fenland, INTERVAL, ARIC, and FinnGen-PPP proteomes plus colocalization triangulation, phenome-wide on-target adverse-effect scans, cross-platform Olink/SomaScan replication,
| 1 | ## Version Compatibility |
| 2 | |
| 3 | Reference examples tested with: TwoSampleMR 0.5.11+, MendelianRandomization 0.10+, MR-PRESSO 1.0+, coloc 5.2.3+, susieR 0.12.35+, ieugwasr 1.0+, plink2 2.00a5+, R 4.4+. |
| 4 | |
| 5 | Before using code patterns, verify installed versions match. If versions differ: |
| 6 | - R: `packageVersion('<pkg>')` then `?function_name` to verify parameters |
| 7 | - CLI: `plink2 --version`; VEP `vep --help` |
| 8 | |
| 9 | If code throws OAuth or rate-limit errors from OpenGWAS, or a missing `dataset$N` from coloc, introspect the installed API and adapt the example rather than retrying. UKB-PPP, deCODE, and Fenland summary statistics changed file layouts between 2023 and 2025; verify column headers before passing into `format_data()`. |
| 10 | |
| 11 | # Proteome-Wide Drug-Target Mendelian Randomization |
| 12 | |
| 13 | **"Does genetically lowering plasma protein X cause a change in disease Y, mimicking a drug?"** -> Use cis-pQTLs in the gene window for protein X as instruments under the Schmidt 2020 framework (Nat Commun 11:3255), restrict the exclusion-restriction violation to the geometric neighbourhood of the encoding gene, triangulate with colocalization (3-tier PP.H4 ladder below) and cross-platform replication (Olink vs SomaScan), and flag protein-altering-variant (PAV) confounding. A single significant cis-MR estimate is necessary but not sufficient for a drug-target claim; the operational bar is MR + coloc + cross-platform agreement + PAV-excluded sensitivity. |
| 14 | |
| 15 | ### PP.H4 Three-Tier Threshold Ladder |
| 16 | |
| 17 | | Tier | PP.H4 | Use case | |
| 18 | |------|-------|----------| |
| 19 | | Suggestive | >= 0.7 | Open Targets / exploratory; consistent with shared-causal | |
| 20 | | Standard publication | >= 0.8 | Wallace 2020 PLoS Genet 16:e1008720; most peer-reviewed pubs | |
| 21 | | Industry / clinical | >= 0.95 | Drug-claim grade; pharma internal target-validation standard | |
| 22 | |
| 23 | Operational rule: drug-target nomination requires PP.H4 >= 0.8 minimum; industry-grade clinical claim requires PP.H4 >= 0.95 plus the full triangulation panel. |
| 24 | |
| 25 | - R (canonical): `TwoSampleMR::mr()` orchestrates the cis-IVW + Egger + median + Wald-ratio panel |
| 26 | - R (correlated cis-pQTLs in a window): `MendelianRandomization::mr_input(..., correlation = ld_matrix)` then `mr_ivw(mr_obj, model='default', correl = TRUE)` |
| 27 | - R (triangulation): `coloc::coloc.abf()` or `coloc::coloc.susie()` on the same cis-window |
| 28 | - pheWAS: `ieugwasr::associations()` against the OpenGWAS catalogue, looped over outcomes |
| 29 | - VEP CLI: annotate every cis-pQTL with `vep --species homo_sapiens --canonical --check_existing` for PAV flagging |
| 30 | |
| 31 | ## Data Source Taxonomy |
| 32 | |
| 33 | | pQTL dataset | Platform | N | Proteins | Reference | Fails when | |
| 34 | |--------------|----------|---|----------|-----------|------------| |
| 35 | | UKB-PPP | Olink Explore 3072 (antibody PEA) | 54,219 | 2923 (54k primary cis-pQTLs across studies; 14,287 primary pQTLs across cis+trans) | Sun 2023 Nature 622:329 | Target not on Olink panel; ancestry mostly EUR; antibody epitope may miss isoforms | |
| 36 | | deCODE | SomaScan v4 (aptamer SOMAmer) | 35,559 | 4907 | Ferkingstad 2021 Nat Genet 53:1712 | Population isolate; LD differs from outbred EUR; aptamers can be PAV-confounded | |
| 37 | | Fenland | SomaScan v4 | 10,708 | 4775 | Pietzner 2021 Science 374:eabj1541 | UK Fenland-specific ascertainment; SomaScan caveats | |
| 38 | | INTERVAL | SomaScan v3 (older) | 3301 | 3622 | Sun 2018 Nature 558:73 | Smaller N; older SomaScan version; useful only as replication | |
| 39 | | ARIC | SomaScan v4 | ~7000 (multi-ancestry sub-cohorts) | 4877 | Zhang 2022 Nat Genet 54:593 | Stratify by ancestry; do not pool | |
| 40 | | FinnGen-PPP | Olink Explore | ~12,000 | ~3000 | FinnGen DF12 (2024 release) | Finnish-specific allele frequencies; not always meta-analyse with UKB | |
| 41 | | AGES-Reykjavik | SomaScan v4 | ~5400 | 4782 | Emilsson 2018 Science 361:769 | Elderly Icelandic cohort; ascertainment bias | |
| 42 | | Olink Explore 1536 disease-specific cohorts (CARDIoGRAMplusC4D, etc) | Olink Explore subset | varies | varies | per-study | Lower N per cohort; use as replication | |
| 43 | |
| 44 | Methodology evolves; check the UKB-PPP portal (ukb-ppp.gwas.eu), deCODE Genetics summary-stat releases, and the eQTL Catalogue / GTEx Portal for the current data version. UKB-PPP was substantially re-released in 2024 (extended anc |