In this study, we found that GDF6 expression was significantly positively correlated with tumor mutational burden (TMB) in colorectal cancer (COAD), microsatellite instability (MSI) in testicular germ cell tumors (TGCT), and homologous recombination deficiency (HRD) in lung adenocarcinoma (LUAD). The gene discussed is GDF6; the disease is lung adenocarcinoma.