Chunk #29 — Results — Determinants of GWAS power and PGS R2 — Sample size and CGR

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Meta-GWAS Accuracy and Power (MetaGAP) Calculator Shows that Hiding Heritability Is Partially Due to Imperfect Genetic Correlations across Studies.

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while the R2 of the PGS is 8.5%, which is only 17% of hSNP2. Thus, R2 is far more sensitive to an imperfect CGR than the meta-analytic power is. This finding is also supported by the approximations of power in Eq 1 and of PGS R2 in Eq 2; these expressions show that, for two discovery studies, the CGR has a linear effect on the variance of the meta-analysis Z statistic, whereas, for one discovery and one hold-out sample, the PGS R2 is quadratically proportional to the CGR.