Table 3. Estimates of causal effect size for BMI and lung function traits.

Population	Trait 1	Trait 2	Direction	Causal effect size	SE	P	nsnp
East Asian	BMI	FEV1	→	-0.0773	0.021	2.46E-04	68
			←	0.0884	0.033	6.53E-03	17
		FVC	→	-0.1084	0.021	3.44E-07	67
			←*	NA	NA	NA	6
		FEV1/FVC	→	0.0332	0.021	0.115732	69
			←*	NA	NA	NA	3
European	BMI	FEV1	→	-0.1057	0.012	4.65E-18	50
			←	0.0250	0.012	0.0308	411
		FVC	→	-0.1564	0.012	1.23E-37	50
			←	-0.0180	0.013	0.154475	379
		FEV1/FVC	→	0.1622	0.014	8.01E-33	48
			←	0.0393	0.009	4.75E-06	599

Note: “→” refers to the trait 1→trait 2 causal direction; “←” refers to the trait 2→trait 1 causal direction; nSNP is number of SNPs in the instrumental variable; causal effect sizes are in unit of per standard deviation increase in exposure.

^*the FVC and FEV1/FVC GWASs do not have enough SNPs at the genome-wide significance level for constructing the instrument variable;