Abstract
BackgroundThe t(1;19)(q23;p13), which can result in the TCF3-PBX1 chimeric gene, is one of the most frequent translocations in B-acute lymphoblastic leukemia (B-ALL) and is observed in both adult and pediatric populations at an overall frequency of 6%. It can occur in a balanced or unbalanced form and as a sole abnormality is associated with an intermediate prognosis. Additionally, this translocation is observed in the context of hyperdiploid B-ALL, in which case it is associated with a poor prognosis. However, due to different translocation partner genes at chromosomes 1 and 19, distinct subtypes of hyperdiploid B-ALL with t(1;19)/der(19)t(1;19) are recognized based on the presence or absence of the TCF3-PBX1 fusion gene, but the cytogenetic and etiologic differences between the two remain understudied.FindingsWe report a case of an adult with a history of relapsed precursor B-ALL whose conventional cytogenetics showed an abnormal female karyotype with both hyperdiploidy and a t(1;19)(q23;p13). Fluorescence in situ hybridization (FISH) on previously G-banded metaphases using the LSI TCF3/PBX1 Dual Color, Dual Fusion Translocation Probe confirmed the presence of the TCF3-PBX1 gene fusion.ConclusionsThis particular pattern with a TCF3-PBX1 fusion within the context of a hyperdiploid karyotype is seen in B-ALL and is usually associated with a poor outcome. This case is one of only a few cases with both hyperdiploidy and a confirmed TCF3-PBX1 fusion, demonstrating the importance of using FISH for proper molecular classification of these cases in order to distinguish them from those with hyperdiploidy but no TCF3-PBX1 fusion gene. Such molecular studies may provide insight into the precise differences between TCF3-PBX1 positive and negative hyperdiploid B-ALL bearing the t(1;19)(q23;p13).
Highlights
The t(1;19)(q23;p13) is one of the most frequent translocations in B-acute lymphoblastic leukemia (B-ALL), and is observed in both adult and pediatric populations at an overall frequency of 6%
This particular pattern with a TCF3-PBX1 fusion within the context of a hyperdiploid karyotype is seen in B-ALL and is usually associated with a poor outcome
The cytogenetic and etiologic differences between TCF3-PBX1 positive and negative B-ALL with hyperdiploidy and t(1;19)/der(19)t(1;19) remain understudied due to lack of molecular classification of the cases reported in the literature
Summary
The t(1;19)(q23;p13) is one of the most frequent translocations in B-acute lymphoblastic leukemia (B-ALL), and is observed in both adult and pediatric populations at an overall frequency of 6% This translocation can occur in a balanced – t (1;19)(q23;p13) – or unbalanced – der (19)t(1;19)(q23;p13) – form and can result in the fusion of TCF3 (transcription factor 3) found at 19p13 and PBX1 (pre-B cell leukemia homebox 1) found at 1q23 to form a chimeric gene whose protein product alters cell differentiation arrest, among other cellular processes [1]. The t(1;19)(q23;p13), which can result in the TCF3-PBX1 chimeric gene, is one of the most frequent translocations in B-acute lymphoblastic leukemia (B-ALL) and is observed in both adult and pediatric populations at an overall frequency of 6% It can occur in a balanced or unbalanced form and as a sole abnormality is associated with an intermediate prognosis. Due to different translocation partner genes at chromosomes 1 and 19, distinct subtypes of hyperdiploid B-ALL with t(1;19)/der(19)t(1;19) are recognized based on the presence or absence of the TCF3-PBX1 fusion gene, but the cytogenetic and etiologic differences between the two remain understudied
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