Lab Med Online.  2023 Apr;13(2):109-113. 10.47429/lmo.2023.13.2.109.

A Case of T-Lymphoblastic Leukemia with Submicroscopic 1p33 Deletion Resulting in STIL-TAL1 Fusion

• Chang SH

• KMID: 2552734
• DOI: http://doi.org/10.47429/lmo.2023.13.2.109

Abstract

T-lymphoblastic leukemia (T-ALL) is an aggressive hematologic malignancy associated with poor outcomes. The genetic background of T-ALL is widely heterogeneous and the TAL1 gene is overexpressed in approximately half of all cases. A submicroscopic interstitial deletion on chromosome 1p33 results inSTIL-TAL1 fusion, causing inappropriate overexpression of TAL1, which promotes T cell leukemogenesis. T-ALL with STIL-TAL1 exhibits distinct characteristics, such as a mature cortical T cell immunophenotype, low incidence of NOTCH1 mutation, privileged association with PTEN inactivation, deletion of 6q14–q16, MYC translocation, high leukocyte count, poor response to treatment, and low event-free survival. However, the clinical relevance and prognostic value of this rearrangement remain unclear. Here, we report the first case of T-ALL with a 1p33 deletion resulting in STIL-TAL1 fusion in Korea, which was detected by reverse transcriptase-polymerase chain reaction and confirmed by chromosomal microarray analysis.

Keyword

T-lymphoblastic leukemia; 1p33 deletion; STIL-TAL1 fusion; Reverse transcriptase-polymerase chain reaction; Microarray

Figure

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  Fig. 1 Morphology of blasts in a peripheral blood smear (A) and bone marrow aspirate smear (B).

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  Fig. 2 Detection of the STIL-TAL1 fusion transcript resulting from 1p33 deletion by multiplex RT-PCR. The screening kit produced a single band in the M3 lane (A), and the split-out kit produced a single 191-base pair band in the M3D lane at diagnosis (B). The split-out kit revealed no band in the M3D lane in the follow-up study one month later (C).

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  Fig. 3 Cytogenetic findings. The karyotype showing 46,XY,del (6)(q21q23) (A). Chromosomal microarray analysis showing arr 1p33(47,700,108–47,763,403)×1 (B).

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