325: cis-pcQTL mapping reveals allelic proxitropy across neighboring human genes

Lawrence et al., The American Journal of Human Genetics - Using a cis-principal-component (pcQTL) approach in human GTEx tissues, the authors uncover novel multi-gene regulatory variants and 33% more GWAS colocalizations than single-gene eQTLs. Key terms: pcQTL, allelic proxitropy, GTEx, colocalization, HOXB.

Study Highlights:
The study analyzes 13 human GTEx tissues and identifies clusters of co-expressed neighboring genes, then applies PCA to cluster expression and maps cis-principal-component QTLs (pcQTLs). pcQTL discovery and fine-mapping used SuSiE and TensorQTL permutation-based FDR to identify an average of ~1,396 pcQTLs per tissue, ~27% of which were not found by single-gene eQTL mapping. pcQTLs tend to represent smaller effects distributed across multiple genes in a cluster and often colocalize with GWAS hits missed by single-gene methods. Functionally, pcQTLs increased GWAS colocalizations by 33%, highlighting multi-gene regulatory proxitropy as a source of complex-trait-associated variation.

Conclusion:
Cis-multi-gene pcQTL mapping uncovers novel regulatory loci and increases GWAS colocalizations compared with single-gene analyses, demonstrating that multi-gene approaches improve detection and interpretation of complex-trait-associated variants.

Music:
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Article title:
Focus on single-gene effects limits discovery and interpretation of complex-trait-associated variants

First author:
Lawrence

Journal:
The American Journal of Human Genetics

DOI:
10.1016/j.ajhg.2026.02.022

Reference:
Lawrence, K.A., Gjorgjieva, T., Nachun, D., and Montgomery, S.B. (2026). Focus on single-gene effects limits discovery and interpretation of complex-trait-associated variants. The American Journal of Human Genetics 113, 1–10. https://doi.org/10.1016/j.ajhg.2026.02.022

License:
This episode is based on an open-access article published under the Creative Commons Attribution 4.0 International License (CC BY 4.0) - https://creativecommons.org/licenses/by/4.0/

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QC:
This episode was checked against the original article PDF and publication metadata for the episode release published on 2026-03-24.

QC Scope:
- article metadata and core scientific claims from the narration
- excludes analogies, intro/outro, and music
- transcript coverage: Audited the transcript sections presenting the conceptual shift to neighborhood gene regulation (allelic proxytropy), the cis-pcQTL (pcQTL) methodology, GTEx tissue clustering, key quantitative results (novel pcQTLs, clusters, colocalizations), and concrete examples (HOXB cluster, IL-18 receptor genes), plus discussion
- transcript topics: Conceptual shift to gene neighborhoods and allelic proxytropy; cis-pcQTL (pcQTL) methodology and PCA-based signal extraction; GTEx tissue clusters and gene-neighborhood calling; pcQTL discovery statistics (clusters, pcQTLs per tissue, novel signals); pcQTLs and GWAS colocalizations; HOXB cluster example (HOXB3 vs HOXB4) and PC4

QC Summary:
- factual score: 10/10
- metadata score: 10/10
- supported core claims: 6
- claims flagged for review: 0
- metadata checks passed: 4
- metadata issues found: 0

Metadata Audited:
- article_doi
- article_title
- article_journal
- license

Factual Items Audited:
- pcQTLs reveal novel multi-gene regulatory variants missed by single-gene eQTLs
- average pcQTLs per tissue is 1,396
- 27% of pcQTL signals are novel (4,859 pcQTLs)
- pcQTLs increase GWAS colocalizations by 33% vs single-gene QTLs
- HOXB cluster PC4 captures inverse variation between HOXB3 and HOXB4
- IL-18 receptor cluster (IL18RAP/IL18R1) pcQTL colocalizes with eczema, dermatitis, IBD

QC result: Pass.