Phospholipase C gamma-1 (PLCG1) gene has been found associated with noteworthy T-cell lymphomas like peripheral T-cell lymphoma (PTCL), angioimmunoblastic T-cell lymphoma (AITL), cutaneous T-cell lymphoma (CTCL) and adult T-cell leukemia/lymphoma [5–9]. Here, PLCG1 is linked to adult T-cell leukemia/lymphoma.