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KMID : 0381120210430101143
Genes and Genomics
2021 Volume.43 No. 10 p.1143 ~ p.1155
Towards fine-scale population stratification modeling based on kernel principal component analysis and random forest
Zhang Weiwen

Cheng Lianglun
Huang Guoheng
Abstract
Background: Population stratification modeling is essential in Genome-Wide Association Studies.

Objective: In this paper, we aim to build a fine-scale population stratification model to efficiently infer individual genetic ancestry.

Methods: Kernel Principal Component Analysis (PCA) and random forest are adopted to build the population stratification model, together with parameter optimization. We explore different PCA methods, including standard PCA and kernel PCA to extract relevant features from the genotype data that is transformed by vcf2geno, a pipeline from LASER software. These extracted features are fed into a random forest for ensemble learning. Parameter tuning is performed to jointly find the optimal number of principal components, kernel function for PCA and parameters of the random forest.

Results: Experiments based on HGDP dataset show that kernel PCA with Sigmoid function and Gaussian function can achieve higher prediction accuracy than the standard PCA. Compared to standard PCA with the two principal components, the accuracy by using KPCA-Sigmoid with the optimal number of principal components can achieve around 100% and 200% improvement for East Asian and European populations, respectively.

Conclusion: With the optimal parameter configuration on both PCA and random forest, our proposed method can infer the individual genetic ancestry more accurately, given their variants.
KEYWORD
Association study, Kernel principal component analysis, Population stratification, Random forest
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