Chunk #6 — Methods — Data sources and genetic instruments — Smoking initiation

Source

Evidence for causal effects of lifetime smoking on risk for depression and schizophrenia: a Mendelian randomisation study.

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The most recent GWAS of smoking initiation from the GSCAN consortium identified 378 conditionally independent genome-wide significant SNPs in a sample of 1 232 091 individuals of European ancestry (Liu et al., 2019). The 378 SNPs explain 2% of the variance in smoking initiation (Liu et al., 2019). When smoking initiation was the outcome, summary statistics without 23andMe (N = 599 289) were used.