FISH, ETV6/RUNX1 (TEL/AML1), Translocation (12;21)

Laboratory assay overview

This fluorescence in situ hybridization (FISH) assay detects the ETV6/RUNX1 (TEL/AML1) fusion gene and is used for determining prognosis of patients with acute lymphoblastic leukemia (ALL) and monitoring for recurrence. The ETV6/RUNX1 (TEL/AML1) fusion gene results from the t(12;21)(p13;q22) translocation and is usually undetectable by conventional chromosome analysis [1]. Although it occurs rarely in adults, it is the most common recurrent translocation in B-lineage pediatric ALL (frequency ~25%) [2]. The presence of the ETV6/RUNX1 (TEL/AML1) fusion gene is indicative of ALL with a favorable prognosis partially due to chemosensitivity, especially in patients <10 years of age [2]. Relapses of ALL with ETV6/RUNX1(TEL/AML1) generally occur later than ALL with other recurrent genetic abnormalities and have a significant likelihood of being successfully treated [2]. Therefore, evaluation of this and other recurrent genetic abnormalities aids in risk stratification, treatment decisions, and monitoring disease status. Interpretation of the test results depends on when the test is performed. The presence of the ETV6/RUNX1 (TEL/AML1) fusion gene at diagnosis is indicative of ALL with a favorable prognosis. In patients who are currently being treated or have just completed the treatment regimen, presence of the ETV6/RUNX1 (TEL/AML1) fusion gene indicates residual disease. In patients thought to be in remission, presence of the ETV6/RUNX1 (TEL/AML1) fusion gene indicates recurrent disease. The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings. References 1. National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®). Acute lymphoblastic leukemia. Version 2.2023. Updated July 28, 2023. https://www.nccn.org 2. Kovach AE, et al. B lymphoblastic leukaemia/lymphoma with ETV6::RUNX1 fusion. In: WHO Classification of Tumours Editorial Board. The World Health Organization Classification of Haematolymphoid Tumours. 5 Beta V2 ed. IARC Press; 2022:chap 4. Accessed May 23, 2023. https://tumourclassification.iarc.who.int