Now liveThe Skillselion MCP - thousands of ranked skills, loaded into your agent mid-task. No install.Get it →
mims-harvard avatar

Tooluniverse Polygenic Risk Score

  • 304 installs
  • 1.6k repo stars
  • Updated August 4, 2026
  • mims-harvard/tooluniverse

tooluniverse-polygenic-risk-score is an agent skill that computes and explains polygenic risk scores from GWAS weights and genotype data for developers building population-genetics or health-research agents.

About

tooluniverse-polygenic-risk-score is a ToolUniverse skill from mims-harvard/tooluniverse that scores traits from GWAS summary statistics and individual genotype inputs, then explains calibration limits and population-genetics caveats. The workflow accepts trait-specific weight files, aligns variant identifiers with genotype records, aggregates weighted allele dosages into a polygenic risk score, and surfaces interpretation context including known limitations for ancestry-mismatched cohorts. Developers reach for this skill when prototyping genomics agents, validating PRS pipelines against published GWAS catalogs, or generating explainable risk outputs for bioinformatics notebooks rather than hand-rolling PLINK or PRSice scripts from scratch.

  • Polygenic risk score computation workflows
  • Uses GWAS summary statistics and weights
  • Explains calibration and ancestry limitations
  • ToolUniverse-backed reproducible scoring
  • Supports trait and disease risk reporting

Tooluniverse Polygenic Risk Score by the numbers

  • 304 all-time installs (skills.sh)
  • +5 installs in the week ending Aug 4, 2026 (Skillselion tracking)
  • Ranked #588 of 2,064 Data Science & ML skills by installs in the Skillselion catalog
  • Data as of Aug 5, 2026 (Skillselion catalog sync)
npx skills add https://github.com/mims-harvard/tooluniverse --skill tooluniverse-polygenic-risk-score

Add your badge

Show developers this skill is listed on Skillselion. Paste this into your README.

Listed on Skillselion
Installs304
repo stars1.6k
Last updatedAugust 4, 2026
Repositorymims-harvard/tooluniverse

How do you compute polygenic risk scores from GWAS weights?

Compute and explain polygenic risk scores from GWAS weights and genotype data, including trait-specific scoring, calibration context, and limitations for population genetics agents.

Who is it for?

Bioinformatics or ML engineers building genomics agents who need PRS computation with explicit limitation notes for research prototypes.

Skip if: Clinical diagnostic workflows requiring regulated validation, or teams without genotype data and curated GWAS weight files.

When should I use this skill?

User requests polygenic risk score calculation, GWAS-based trait scoring, or PRS explanation for genotype data.

What you get

Polygenic risk score values, trait-specific weight mappings, and written calibration and population-limitation context.

  • Computed polygenic risk score
  • Trait interpretation and limitation summary

Files

SKILL.mdMarkdownGitHub ↗

Polygenic Risk Score (PRS) Builder

Build and interpret polygenic risk scores for complex diseases using genome-wide association study (GWAS) data.

Reasoning Strategy

A polygenic risk score predicts genetic risk, not disease. A high PRS means elevated risk relative to the population — it does not mean the person will develop the condition, and a low PRS does not confer immunity. PRS performance varies dramatically across ancestries: a European-derived PRS applied to a West African population can lose 50–70% of its predictive power because the underlying GWAS was trained on European allele frequencies and LD patterns. Effect sizes from discovery GWAS are subject to winner's curse (overestimation in single studies); always prefer weights from large meta-analyses or validated PGS Catalog models. PRS should always be interpreted in the context of non-genetic risk factors — for most complex diseases, environmental factors contribute as much or more than genetics.

LOOK UP DON'T GUESS: Do not assume effect sizes, allele frequencies, or which SNPs are genome-wide significant for a trait — always query GWAS Catalog (gwas_get_associations_for_trait) for actual data. Do not assume a validated PRS model exists for a trait; check PGS Catalog via PubMed search.

Overview

Use Cases:

  • "Calculate my genetic risk for type 2 diabetes"
  • "Build a polygenic risk score for coronary artery disease"
  • "What's my genetic predisposition to Alzheimer's disease?"
  • "Interpret my PRS percentile for breast cancer risk"

What This Skill Does:

  • Extracts genome-wide significant variants (p < 5e-8) from GWAS Catalog
  • Builds weighted PRS models using effect sizes (beta coefficients)
  • Calculates individual risk scores from genotype data
  • Interprets PRS as population percentiles and risk categories

What This Skill Does NOT Do:

  • Diagnose disease (PRS is probabilistic, not deterministic)
  • Replace clinical assessment or genetic counseling
  • Account for non-genetic factors (lifestyle, environment)
  • Provide treatment recommendations

Methodology

PRS Calculation Formula

A polygenic risk score is calculated as a weighted sum across genetic variants:

PRS = Σ (dosage_i × effect_size_i)

Where:

  • dosage_i: Number of effect alleles at SNP i (0, 1, or 2)
  • effect_size_i: Beta coefficient or log(odds ratio) from GWAS

Standardization

Raw PRS is standardized to z-scores for interpretation:

z-score = (PRS - population_mean) / population_std

This allows comparison to population distribution and percentile calculation.

Significance Thresholds

  • Genome-wide significance: p < 5×10⁻⁸ (default threshold)
  • This corrects for ~1 million independent tests across the genome
  • Relaxed thresholds (e.g., p < 1×10⁻⁵) can include more SNPs but may add noise

Effect Size Handling

  • Continuous traits (e.g., height, BMI): Beta coefficient (units of trait per allele)
  • Binary traits (e.g., disease): Odds ratio converted to log-odds (beta = ln(OR))
  • Missing effect sizes or non-significant SNPs are excluded

Data Sources

This skill uses ToolUniverse GWAS tools to query:

1. GWAS Catalog (EMBL-EBI)

  • Curated GWAS associations, 5000+ studies
  • Tools: gwas_search_associations (param: disease_trait, size; also gwas_get_associations_for_trait), gwas_get_snps_for_gene (param: gene_symbol), dbsnp_get_variant_by_rsid
  • Note: disease_trait search returns associations where the trait is one of potentially several linked EFO traits. For precise filtering, use EFO IDs via efo_trait param.

2. Open Targets Genetics

  • Integrated genetics platform with fine-mapped credible sets
  • Tools: OpenTargets_search_gwas_studies_by_disease, EnsemblVEP_annotate_hgvs (for variant consequence/frequency)

3. Variant Annotation

  • gnomad_search_variants + gnomad_get_variant — population allele frequencies (ancestry-specific via VEP colocated_variants)
  • MyVariant_query_variants — CADD, SIFT, PolyPhen, ClinVar, gnomAD in one call
  • gnomad_get_gene_constraints — gene constraint metrics (pLI, oe_lof) for target prioritization

Key Concepts

Polygenic Risk Scores (PRS)

Polygenic risk scores aggregate the effects of many genetic variants to estimate an individual's genetic predisposition to a trait or disease. Unlike Mendelian diseases caused by single mutations, complex diseases involve hundreds to thousands of variants, each with small effects.

Key Properties:

  • Continuous distribution: PRS forms a bell curve in populations
  • Relative risk: Compares individual to population average
  • Probabilistic: High PRS doesn't guarantee disease, low PRS doesn't guarantee protection
  • Ancestry-specific: PRS accuracy depends on matching GWAS and target ancestry

GWAS (Genome-Wide Association Studies)

GWAS compare allele frequencies between cases and controls (or correlate with trait values) across millions of SNPs to identify disease-associated variants.

Study Design:

  • Discovery cohort: Initial identification of associations
  • Replication cohort: Validation in independent samples
  • Sample size: Larger studies detect smaller effects (power ∝ √N)
  • Multiple testing correction: Bonferroni-type correction for ~1M tests

Effect Sizes and Odds Ratios

  • Beta (β): Change in trait per copy of effect allele
  • Example: β = 0.5 kg/m² means each allele increases BMI by 0.5 units
  • Odds Ratio (OR): Multiplicative change in disease odds
  • OR = 1.5 means 50% increased odds per allele
  • Convert to beta: β = ln(OR)

Linkage Disequilibrium (LD) and Clumping

Nearby variants are often inherited together (LD). To avoid double-counting:

  • LD clumping: Select independent variants (r² < 0.1 within 1 Mb windows)
  • Fine-mapping: Statistical methods to identify causal variants
  • This skill uses raw associations; production PRS should include LD pruning

Population Stratification

GWAS and PRS are most accurate when ancestries match:

  • Population structure: Different ancestries have different allele frequencies
  • Transferability: European-trained PRS perform worse in non-European populations
  • Solution: Train PRS on diverse cohorts or use ancestry-matched references

Applications

Clinical Risk Assessment

PRS can stratify individuals for:

  • Screening programs: Target high-risk individuals (e.g., mammography, colonoscopy)
  • Prevention strategies: Lifestyle interventions for high genetic risk
  • Drug response: Pharmacogenomics based on metabolism genes

Example: Khera et al. (2018) showed PRS identifies 3× more individuals at >3-fold coronary artery disease risk than monogenic mutations.

Research Applications

  • Gene discovery: PRS-based phenome-wide association studies (PheWAS)
  • Genetic correlation: Compare PRS across traits
  • Causal inference: Mendelian randomization using PRS as instruments
  • Simulation studies: Model polygenic architecture

Personal Genomics

Consumer genetic testing (23andMe, Ancestry DNA) provides raw genotypes. Users can:

  • Calculate PRS for traits not reported
  • Compare to published PRS models
  • Understand genetic contribution vs. lifestyle factors

Caution: Personal PRS should not replace medical advice. Results may cause anxiety if not properly contextualized.

Limitations and Considerations

  • Heritability gap: PRS explains only a fraction of genetic heritability (T2D: ~50% heritable, PRS explains ~10–20%). Rare variants, epistasis, and gene-environment interactions are not captured.
  • Ancestry bias: European-derived PRS performance drops substantially in non-European populations. Use multi-ancestry GWAS weights when available.
  • Winner's curse: Discovery effect sizes are overestimated; use meta-analysis weights or PGS Catalog validated models.
  • Not diagnostic: High PRS does not guarantee disease; low PRS does not guarantee protection. Environmental factors contribute equally or more for most complex diseases.
  • Actionability varies: Alzheimer's PRS has limited actionable interventions; cardiovascular PRS can guide statin or lifestyle decisions. Always consider what the person can do with the information.
  • Ethical: Genetic data is permanent and familial. GINA protects employment/health insurance in the US, but not life insurance. Provide genetic counseling context.

Workflow

1. Trait Selection

Identify the disease or trait of interest:

  • Use standard terminology (e.g., "type 2 diabetes" not "T2D")
  • Check GWAS Catalog for availability
  • Verify sufficient GWAS studies exist (n > 10,000 samples ideal)

2. Association Collection

Query GWAS databases for genome-wide significant associations:

prs = build_polygenic_risk_score(
    trait="coronary artery disease",
    p_threshold=5e-8,  # Genome-wide significance
    max_snps=1000
)

Considerations:

  • P-value threshold: 5e-8 is conservative, 1e-5 includes more variants
  • LD clumping: Production systems should prune correlated SNPs
  • Study quality: Prefer large meta-analyses over small studies

3. Effect Size Extraction

Extract beta coefficients or odds ratios:

  • Beta for continuous traits (direct use)
  • OR for binary traits (convert to log-odds)
  • Handle missing values (exclude or impute from meta-analysis)

4. SNP Filtering

Quality control filters:

  • MAF filter: Exclude rare variants (MAF < 0.01) for robustness
  • Genotype QC: Remove SNPs with high missingness (> 10%)
  • Hardy-Weinberg: Exclude SNPs violating HWE (p < 1e-6)
  • Ambiguous SNPs: Remove A/T and G/C SNPs (strand ambiguity)

5. Score Calculation

Calculate weighted sum of genotype dosages:

result = calculate_personal_prs(
    prs_weights=prs,
    genotypes=my_genotypes,
    population_mean=0.0,
    population_std=1.0
)

Genotype Sources:

  • 23andMe raw data export
  • Ancestry DNA raw data
  • Whole genome sequencing (VCF files)
  • SNP array data (Illumina, Affymetrix)

6. Risk Interpretation

Convert to percentiles and risk categories:

result = interpret_prs_percentile(result)
print(f"Percentile: {result.percentile:.1f}%")
print(f"Risk: {result.risk_category}")

Risk Categories:

  • Low risk: < 20th percentile (genetic protection)
  • Average risk: 20-80th percentile (typical genetic predisposition)
  • Elevated risk: 80-95th percentile (moderately increased risk)
  • High risk: > 95th percentile (substantially increased risk)

Clinical Interpretation:

  • Percentiles assume normal distribution
  • Relative risk vs. average (not absolute risk)
  • Combine with family history, clinical risk factors
  • PRS is NOT diagnostic - many high-risk individuals never develop disease

Best Practices

  • Use validated PRS from PGS Catalog when available (externally validated, includes LD clumping and ancestry-specific weights)
  • Match ancestries between GWAS and target population; use multi-ancestry GWAS when available
  • For highly polygenic traits (height, education), relaxed p-value thresholds capture more signal; for oligogenic traits (IBD, T1D), strict thresholds are better
  • Combine PRS with clinical risk scores (Framingham, QRISK) for integrated prediction
  • In research: document SNP selection criteria, LD clumping parameters, and ancestry of GWAS; validate in held-out cohorts; report R² or AUC stratified by ancestry

Disclaimer

This skill is for educational and research purposes only.

  • Not for clinical diagnosis or treatment decisions
  • Not validated for clinical use - use PGS Catalog models for clinical-grade PRS
  • Requires genetic counseling - interpretation requires expertise
  • Does not account for family history, environment, or lifestyle factors
  • Ancestry-specific - accuracy depends on matching GWAS ancestry

For clinical genetic testing, consult:

  • Genetic counselors (certified by ABGC/ABMGG)
  • Medical geneticists
  • Healthcare providers with genomics training

PRS is a rapidly evolving field. Guidelines and best practices will continue to change as research progresses.

Regulatory Status:

  • FDA does not currently regulate PRS (as of 2024)
  • Some countries restrict direct-to-consumer genetic risk reporting
  • Check local regulations before clinical implementation

Related skills

FAQ

What inputs does tooluniverse-polygenic-risk-score need?

tooluniverse-polygenic-risk-score expects trait-specific GWAS weight data and individual genotype records with alignable variant identifiers. Without both weight files and genotype inputs, the skill cannot produce a calibrated polygenic risk score.

Can tooluniverse-polygenic-risk-score be used for clinical diagnosis?

tooluniverse-polygenic-risk-score is designed for research agents and explicitly surfaces population-genetics limitations and calibration caveats. Clinical diagnostic use requires regulated validation pipelines beyond what this research-oriented skill provides.

Data Science & MLanalyticspipelines

This week in AI coding

Five minutes, every Monday - the tools, releases and tactics for developers.

unsubscribe anytime.