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Local-Ancestry GWAS (Tractor)

Definition
AI-generated

Tractor is a framework that uses local ancestry calls in admixed individuals to partition genotypes by ancestral background and perform association tests that recover ancestry-specific allele–trait relationships.

Topics
Population genetics
Related
Admixture Admixture Mapping Ancestry

Why it matters in GWAS

Large, admixed cohorts (e.g. African American, Latino) carry signal that standard PCA adjustment may underuse; Tractor and related approaches improve power and interpretability for loci where effects or tagging differ by ancestry tract.

Example usage

"We ran Tractor on the admixed panel to estimate European- and African-localized effects at the replicated blood-pressure locus."

Admixture Admixture Mapping Ancestry Local Ancestry Polygenic Risk Score Portability Trans-Ancestry GWAS
Related-term network

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Node order. The current term is first. Next come every page linked from Related terms, in the same top-to-bottom order as that list. Then new terms appear in two-hop layers: for each of those direct neighbors (in that same order), their related terms are appended if not already listed. A third pass does the same for two-hop nodes. The walk stops when a fixed maximum number of nodes is reached.

References

  • Atkinson EG, et al. (2021). Tractor uses local ancestry to enable the inclusion of admixed individuals in GWAS and to boost power. Nat Genet.
  • Kuchenbaecker K, Navoly G. (2026). Ancestral diversity in complex disease genetics: from discovery to translation. Nat Rev Genet. https://doi.org/10.1038/s41576-025-00921-3
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