The presence of heterogeneity in the MR analysis for PSMA4, without evidence of directional pleiotropy, suggests that while there may be variation in the effect of genetic instruments, the overall association with lung cancer risk is not biased (Birney, 2022; Yuan et al., 2022; Papadimitriou et al., 2020). The gene discussed is PSMA4; the disease is lung carcinoma.