East Asians often develop type 2 diabetes at a substantially lower BMI than Europeans. Does this mean that the genetic architecture of the disease is different? 🧬
A recent
@CommsBio study addressed this question using a GWAS of almost 600,000 people of East Asian ancestry and a European GWAS of comparable statistical power.
Surprisingly, the overall picture was very similar. The studies identified 196 loci in East Asians and 199 in Europeans. Fine-mapping identified 521 likely causal signals, and about 74% were shared between the two populations.
But differences emerged when the authors looked deeper into the biology. Type 2 diabetes develops mainly through two related mechanisms: insufficient insulin secretion by pancreatic β cells and insulin resistance, strongly influenced by adipose tissue, lipid metabolism and obesity.
In both populations, GWAS signals were strongly enriched in regulatory regions active in pancreatic β cells. Yet the regulatory architecture differed: HNF1B-related regions were more enriched in East Asians, while PDX1-related regions were more prominent in Europeans. Europeans also showed a stronger genetic component related to adipose tissue and lipid metabolism.
The authors then used previously developed polygenic scores representing insulin secretion and insulin resistance. Among controls, the scores were almost identical between Japanese and British participants. But among people with diabetes, both effects were stronger in Europeans: OR 1.40 vs 1.21 for insulin secretion and OR 1.35 vs 1.18 for insulin resistance.
This raises an interesting question. Do East Asians have a lower threshold for developing diabetes, requiring less polygenic burden? Or do these mechanistic PRS simply work better in Europeans?
Still, PRS performed quite well in an independent Taiwanese cohort: a model combining age, sex, genetic PCs and PRS reached AUC ~0.8.
Overall, this looks like the same polygenic system with somewhat different weights assigned to its components across populations.
nature.com/articles/s42003-0…
#T2D #GWAS #PRS