| Summary: | 碩士 === 國立臺灣大學 === 流行病學與預防醫學研究所 === 102 === Schizophrenia is considered to be genetically and phenotypically heterogeneous. The high heritability of neurocognitive impairments found in patients with schizophrenia suggests that these impairments may serve as an endophenotype resulting from a set of underlying genes in a mode of polygenic effects. In this study, a total of 165 schizophrenia patients were selected and these subjects were subjected to genotyping for 642,832 single nucleotide polymorphisms (SNPs). After quality control, 564,110 SNPs were left. We then performed principal component analysis (PCA) on 14 indices of the Continuous Performance Test (CPT) and the Wisconsin Card Sorting Test (WCST). Two orthogonal principal components (PC1 and PC2) identified with PCA explained 36.11% and 18.30% of the total variance, respectively. Then the two PCs were investigated for association with SNPs. Because of small sample size in this study, however, we were unable to detect SNPs associated with neurocognitive performance in schizophrenia with genome-wide significance. For exploring the polygenic effect, polygenic score analysis was conducted on 240,579 LD-based pruning SNPs (r2 > 0.5), which were imputed using MaCH and MiniMac. The sample was first randomly divided into a learning set (n = 83) and a test set (n = 82). Then the effect size (β) for the results of association test in the learning set was used to develop a linear model to generate scores in the test set. The sustained attention demonstrated a significant association (p = 0.03) with the PC1 polygenic score at a threshold of p = 0.0001 (25 markers), For the executive function, when polygenic scores in the test set was calculated based on the results of the best 0.1% of SNPs (219 markers) in the association study of learning set.
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