Leukemia - Acute
B lymphoblastic leukemia / lymphoma with t(1;19)(q23;p13.3); E2A-PBX1 (TCF3-PBX1)
Reviewer: Daniela Mihova, M.D. (see Reviewers page)
Revised: 2 February 2013, last major update September 2012
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● 5-6% of ALL; commonly detected by conventional cytogenetics in children
● E2A-PBX1 (TCF3-PBX1) is chimeric gene formed by t(1;19)(q23;p13.3) (Mol Cell Biol 1994;14:3938)
● High WBC counts, frequent CNS involvement
● In children (Blood 1984;63:721) and adults (Haematologica 2010;95:241), is no longer a poor prognostic factor, due to intensive therapy and bone marrow transplantation
● Child with t(1;19) without fusion transcript by PCR or Southern blot (Rinsho Ketsueki 2005;46:7)
● No distinct morphologic findings
● Typical immunophenotype cytoplasmic µ (cµ), CD10, CD19
● If cytoplasmic µ negative, can be suspected if strong CD9 and CD34-
● Produces fusion transcript of PBX1 and E2A; occurs in balanced and unbalanced forms; unbalanced form is der(19)t(1;19)
● The reciprocal product of der(1)t(1;19) is lost and the normal chromosome 1 is duplicated (Leukemia 2001;15:95, Atlas of Genetics and Cytogenetics in Oncology and Haematology)
● “Unbalanced translocations” means the exchange of chromosomal material is unequal, resulting in extra or missing genes
● “der” means derivative chromosome - term is used when only one chromosome from a translocation is present, or when one chromosome has two or more structural abnormalities
Karyotype (unbalanced) with loss of der(1)t(1;19)
End of Leukemia - Acute > PreB ALL > B lymphoblastic leukemia / lymphoma with t(1;19)(q23;p13.3); E2A-PBX1 (TCF3-PBX1)
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