PLLP and small cell lung carcinoma: DEGs further intersect with the closely related genes of SCLC from the results of MR analysis, we obtained two up-regulated CEGs (PSAT1, PSRC1) and three down-regulated CEGs (COLEC12, PLLP, HP), and MR analysis confirmed that increased expression of PSAT1 and PSRC1 were associated with increased risk of SCLC, while decreased expression of COLEC12, PLLP, and HP were associated with increased risk of SCLC, suggesting that they may play a key role in the pathogenesis of SCLC.