Ancestry-Specific T2D Genetic Mechanisms

The genetic mechanisms driving T2D are not uniform across populations. Over 600 T2D-associated loci have been identified by GWAS, but their contributions to disease risk vary significantly across ancestry groups due to allele frequency differences, population-specific variants, and ancestry-specific genetic architecture.

Population-Level Patterns

  • East Asian populations tend to have a higher prevalence of beta-cell dysfunction as the primary T2D mechanism, while European populations more often exhibit insulin resistance-driven disease. This pattern was documented by Yabe et al. 2015 and confirmed in our prior work (Markelova et al. 2025) in Yakut populations (genetically close to East Asians), using the same cohort analyzed in the current project.
  • The Yakut population showed elevated partitioned polygenic scores for Beta Cell 1 (reduced insulin response) and Hyper Insulin (compensatory insulin production) clusters simultaneously, with no correlation between them — suggesting these opposing mechanisms are driven by distinct genetic factors within the same population.
  • Yabe et al. 2015 provides the broader literature framework by documenting East-Asian-specific T2D genetic loci (KCNQ1, UBE2E2, C2CD4A/B, PTPRD, SRR, SPRY2, CDC123) that predominantly implicate β-cell function — the same functional axis that distinguishes Yakut (β-cell dominant) from Chechen and Tatar (obesity/insulin-resistance dominant) T2D mechanisms in our same-cohort prior work (Markelova et al. 2025).
  • Yabe et al. also show that most East Asian T2D loci replicate in non-East Asians, so individual variants do not explain the characteristic β-cell dysfunction — pointing to gene-environment and gene-gene interactions as the likely source. 1

Evidence From Our Prior Work (Same Cohort)

  • Markelova et al. 2025 (our prior work, same cohort as the current project) genotyped Chechen, Tatar, and Yakut populations and found that Yakuts had significantly higher pPGS for Beta Cell 1, Hyper Insulin, and Liver-Lipid clusters, while Chechens and Tatars had higher obesity-related mechanism scores.
  • Chechens exhibited higher BMI than other groups but have a lower prevalence of carbohydrate metabolism disorders, suggesting possible genetic protective factors that decouple obesity from T2D risk.
  • Tatars showed the lowest Hyper Insulin and SHBG-LpA pPGS values, indicating a distinct genetic risk profile.

Relevance To PBMC Immune Phenotypes

Because the current PBMC project uses the same cohort, the link between T2D genetic mechanisms and PBMC immune features is directly testable: we can correlate each individual’s pPGS profile with their PBMC immune measurements. This is not a cross-cohort inference — it is an within-cohort, multi-modal analysis bridging genetics and immunology in the same individuals. The ancestry-specific pPGS patterns established in our prior work serve as the genetic backbone for the PBMC immune analysis, enabling direct joint modeling.

Open Questions

  • Within the same cohort, do ancestry-specific T2D genetic mechanisms (pPGS clusters) correlate with ancestry-specific PBMC immune features?
  • Can pPGS for T2D mechanisms and polygenic scores for immune traits jointly explain ancestry-associated immune variation better than either alone?
  • Do individuals with different predominant T2D genetic mechanisms show different PBMC immune profiles, independent of ancestry?

Sources

  • Markelova et al. 2025 — our prior work, same cohort as the current project
  • Yabe et al. 2015 — β Cell Dysfunction Versus Insulin Resistance in the Pathogenesis of Type 2 Diabetes in East Asians

Footnotes

  1. extracted from Yabe et al. 2015