A genome-wide association study (GWAS) of the personality constructs in CPAI-2 in Taiwanese Hakka populations

Abstract

Here in this study we adopted genome-wide association studies (GWAS) to investigate the genetic components of the personality constructs in the Chinese Personality Assessment Inventory 2 (CPAI-2) in Taiwanese Hakka populations, who are likely the descendants of a recent admixture between a group of Chinese immigrants with high emigration intention and a group of the Taiwanese aboriginal population generally without it. A total of 279 qualified participants were examined and genotyped by an Illumina array with 547,644 SNPs to perform the GWAS. Although our sample size is small and that unavoidably limits our statistical power (Type 2 error but not Type 1 error), we still found three genomic regions showing strong association with Enterprise, Diversity, and Logical vs. Affective Orientation, respectively. Multiple genes around the identified regions were reported to be nervous system related, which suggests that genetic variants underlying the certain personalities should indeed exist in the nearby areas. It is likely that the recent immigration and admixture history of the Taiwanese Hakka people created strong linkage disequilibrium between the emigration intention-related genetic variants and their neighboring genetic markers, so that we could identify them despite with only limited statistical power.

Fig 1. The Manhattan plots of the probability values in linear regression analysis for the 19 personalities.

The horizontal axis in each plot represents the SNP location from chromosome 1 to chromosome 22, while the vertical axis indicates the significance level of that SNP (represented in–log₁₀ format).

Fig 2. Regional association plots around the three most significant SNPs.

(A) SNP rs566661 on chromosome 6 with Enterprise; (B) SNP rs1267992 on chromosome 6 with Diversity; (C) SNP rs12503435 on chromosome 4 with Logical vs. Affective Orientation. SNPs were plotted according to their probability values in the linear regression analysis (Fig 3 as the example) with the corresponding personalities. The purple rhombuses with SNP names are the most significant ones. The colors of the other circles represent their linkage disequilibrium (r²) with the named top SNP. The genomic information denoted below was derived from human genome assembly GRCh37 (hg19) from Genome Reference Consortium.

Fig 3. The linear regressions between the personality score and genotype for the three most significant SNPs in Fig 2.

(A) SNP rs566661 on chromosome 6 with Enterprise. The Pearson correlation coefficient (R) is 0.331 and the regression coefficient (β, the slope) is -1.127; (B) SNP rs1267992 on chromosome 6 with Diversity (R = 0.327 and β = -0.675); (C) SNP rs12503435 on chromosome 4 with Logical vs. Affective Orientation (R = 0.225 and β = 1.078). The personality score and genotype of each participant were used to draw the swarm plots and obtain the regression lines.