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Fine-mapping and TWAS analysis

This mini-protocol selects among univariate, multivariate, multigene, functional and summary-statistic fine-mapping routes according to the available data and analysis goal.

Miniprotocol Timing

Timing: TBD

Overview

The MNM regression module analyzes individual-level genotype and molecular-phenotype data. qtl_dataset_construct+susie_twas performs univariate SuSiE fine-mapping and estimates TWAS weights; mnm jointly analyzes multiple molecular traits with multivariate priors; mnm_genes extends the multivariate model across genes; and fsusie fine-maps functional or epigenomic phenotypes.

The RSS module instead combines GWAS summary statistics with an external LD reference. These five commands are alternative analysis routes rather than a mandatory chain.

Steps

Analysis goalCommands to run, in orderInputs
Univariate molecular-QTL fine-mapping and TWAS weights1Genotype BED set, phenotype manifest, covariates and association windows under input/colocboost/
Multivariate fine-mapping across molecular traits2Step 1 inputs plus tests/fixtures/qtl_mini/fine_mapping_meta.tsv
Multigene multivariate fine-mapping3Multivariate inputs plus phenotype-ID map and retained-sample list under input/colocboost/
Fine-map functional or epigenomic phenotypes4tests/fixtures/qtl_mini/protocol_example.genotype.chr22.bed; phenotype manifest, covariates and windows
GWAS summary-statistic fine-mapping5tests/fixtures/rss_analysis/protocol_example.rss_mwe.gwas_meta.tsv; tests/fixtures/ld_reference/ld_meta_file.tsv

Run only the command matching the analysis goal.

1. Univariate fine-mapping and TWAS

What it does: qtl_dataset_construct+susie_twas builds the regional dataset, fits SuSiE and saves fine-mapping results and cross-validated TWAS weights.

2. Multivariate fine-mapping

What it does: mnm jointly fine-maps multiple molecular traits using the analyses and prior settings specified by the fine-mapping metadata.

3. Multigene multivariate fine-mapping

What it does: mnm_genes coordinates multivariate fine-mapping across genes while preserving phenotype identifiers and a common retained-sample set.

4. Functional fine-mapping

What it does: fsusie applies functional SuSiE to epigenomic or other functional phenotypes and saves posterior fine-mapping results and residual data.

5. Summary-statistic fine-mapping

What it does: the RSS chain harmonizes regional GWAS summary statistics with the LD reference, runs SuSiE-RSS fine-mapping and produces a regional diagnostic plot.

Output

RouteOutput filename and relative pathDescription
Univariateoutput/mnm/univariate/**/*.univariate_bvsr.rds; output/mnm/univariate/**/*.twas_weights.rdsSuSiE posterior and TWAS-weight objects
Multivariateoutput/mnm/multivariate/**/*.multivariate_bvsr.rds; output/mnm/multivariate/**/*.twas_weights.rdsJoint multivariate posterior and weights
Multigeneoutput/mnm/multigene/**/*Per-region, per-gene multivariate results and metadata
Functionaloutput/mnm/fsusie/**/*.fsusie.rds; saved residual objectsFunctional fine-mapping posterior and residual data
RSSoutput/mnm/rss/fine_mapping/AD_Bellenguez_2022.chr22_49355984_50799822.gwas_finemap.rds; regional plot under output/mnm/rss/plots/Summary-statistic fine-mapping result and diagnostic plot

Anticipated Results

Each route produces posterior inclusion probabilities and credible-set information for the selected region and analysis model. Routes that estimate prediction weights also save TWAS-weight objects. The RSS route additionally records the harmonized regional summary statistics and LD-based diagnostics.

Command Interface