This is especially true for patients who test negative for anti-citrullinated protein antibodies.[41] The CD247 molecule, also known as T-cell surface glycoprotein CD3 zeta chain, has potential as a disease severity and prognostic biomarker for Idiopathic pulmonary fibrosis among T-cells.[42] The glycoprotein CD2 is expressed primarily on T and NK cells and serves as a costimulatory receptor.[43] In summary, these 9 genes are correlated with immune responses or with KLRB1, which requires further studies to explore the interaction of these genes with KLRB1 in TGCT. Here, KLRB1 is linked to testicular germ cell tumor.