In a retrospective multicenter study, IDH2R172 mutation was found in 19–45% AITL patients and was correlated with poor survival,339 and different pathologic and clinical features.132,133,340–342 When using plasma cell-free DNA as liquid biopsy for the diagnosis of AITL, IDH2R172 hotspot mutations were detected in 15% of patients.343 Studies found that IDH2 mutation was confined in the malignant T cell of AITL, and that 2-HG was elevated in tumor tissue and serum of patients.344. The gene discussed is IDH2; the disease is angioimmunoblastic T-cell lymphoma.