Detecting Genetic Ancestry and Adaptation in the Taiwanese Han People

Area of Science:

• Human Population Genetics
• Genomics
• Evolutionary Biology

Background:

• The Taiwanese Han population, comprising ~95% of Taiwan's people, may not be genetically homogeneous due to 400 years of migration from diverse East Asian regions.
• Limited understanding exists regarding the genetic ancestry patterns, population admixture, and evolutionary adaptations within the Taiwanese Han.

Purpose of the Study:

• To investigate the genetic ancestry, admixture, and identify signatures of natural selection in the Taiwanese Han population.
• To explore the functional implications of identified genes associated with adaptation and metabolic traits.

Main Methods:

• Analysis of whole-genome single-nucleotide polymorphism (SNP) genotyping data from 14,401 Taiwanese Han individuals (Taiwan Biobank).
• Whole-genome sequencing of a subset of 772 individuals.
• Genome-wide scans for positive natural selection signatures (long-range haplotypes, hitchhiked variants).
• Examination of associations between candidate genes and 16 metabolic-related traits.

Main Results:

• Identification of four major genetic ancestries (Northern, Southeastern, Japonic, Island Southeast Asian) with distinct geographic distributions.
• Detection of significant population admixture contributing to the Taiwanese Han genome.
• Identification of 16 candidate loci with selection signals, localized to five genes: CTNNA2, LRP1B, CSNK1G3, ASTN2, and NEO1.
• All five identified genes exhibit pleiotropic effects on disease susceptibility and significant associations with at least one metabolic trait.

Conclusions:

• The study provides critical insights into the evolutionary history and adaptive processes of the Taiwanese Han population.
• The identified genes (CTNNA2, LRP1B, CSNK1G3, ASTN2, NEO1) are important targets for understanding human adaptation and metabolic health in this population.