19p E2A

Laboratory assay overview

This panel uses fluorescence in situ hybridization (FISH) to detect an extended set of common genetic abnormalities associated with B-cell acute lymphoblastic leukemia (B-ALL) and may aid in risk stratification and treatment decisions. These genetic abnormalities include the following: MYC rearrangement, the CDKN2A deletion, IGH rearrangement, TCF3 (E2A) rearrangement resulting from the t(1;19)(q23;p13) translocation, the BCR/ABL1 fusion gene resulting from the t(9;22)(q34;q11.2) translocation, the ETV6/RUNX1 (TEL/AML1) fusion gene resulting from the t(12;21)(p13;q22) translocation, KMT2A (MLL) rearrangement, intrachromosomal amplification of chromosome 21 (iAMP21), and trisomy of chromosomes 4, 10, and 17.While laboratory diagnosis of B-ALL generally requires morphologic evaluation and immunophenotyping, identifying genetic abnormalities is essential for risk stratification and patient management [1,2]. The College of American Pathologists and the American Society of Hematology recommend testing children with suspected or confirmed B-ALL for the following: the BCR/ABL1 fusion gene resulting from the t(9;22)(q34;q11.2) translocation, the ETV6/RUNX1 fusion gene resulting from the t(12;21)(p13;q22) translocation, KMT2A translocation, iAMP21, and trisomy 4 and 10 [3].A combination of genetic techniques is often involved in identifying genetic abnormalities. FISH testing is complementary to conventional cytogenetic analysis (karyotyping) and can be used to detect common cytogenetic abnormalities, especially cryptic ones not identified by karyotyping, such as the ETV6/RUNX1 fusion gene caused by t(12;21)(p13;q22) and iAMP21 (also detectable with FISH for ETV6/RUNX1) [1,2]. However, because FISH is limited to probing specific chromosomal regions, it does not replace conventional cytogenetic analysis or chromosomal microarray for screening unknown abnormalities.|The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings.References1. Naresh KN, et al. B-cell lymphoid proliferations and lymphomas. 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 June 8, 2023. https://tumourclassification.iarc.who.int2. 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.org3. Arber DA, et al. Arch Pathol Lab Med. 2017;141(10):1342-1393