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Mixed phenotype acute leukaemia with t(9,22), BCR-ABL1: A case report

Yong WL, Yusof N, Ithnin A, Shuib S, Tumian R, Yousuf R, et al.

Malays J Pathol, 2020 Dec;42(3):469-476.
PMID: 33361731

INTRODUCTION: Mixed phenotype acute leukaemia (MPAL) is a rare entity of acute leukaemia.
CASE REPORT: Here we report a case of a 39-year-old lady, with an incidental finding of hyperleukocytosis (white blood cells count: 139.2 x 109/L). Her peripheral blood film revealed 36% of blasts and a bone marrow aspiration showed 53% of blasts. Immunophenotyping showed a population of blasts exhibiting positivity of two lineages, myeloid lineage and B-lymphoid lineage with strong positivity of CD34 and terminal deoxynucleotidyl transferase (Tdt). A conventional karyotyping revealed the presence of Philadelphia chromosome. She was diagnosed with MPAL with t(9,22), BCR ABL1, which carried a poor prognosis. She was treated with acute lymphoblastic leukaemia (ALL) chemotherapy protocol coupled with a tyrosine kinase inhibitor and was planned for an allogeneic stem cells transplant.
CONCLUSION: This MPAL case was diagnosed incidentally in an asymptomatic patient during medical check-up. We highlight this rare case report to raise the awareness about this rare disease. Understanding the pathogenesis of the disease with the underlying genes responsible for triggering the disease, uniform protocols for diagnosis and targeted treatment will help for proper management of these patients.

Matched MeSH terms: Translocation, Genetic/genetics
A new complex translocation (8;22;21)(q22;q12;q22) in RUNX1/RUNX1T1 acute myeloid leukaemia

Tay Za K, Shanmugam H, Chin EFM

Malays J Pathol, 2019 Dec;41(3):333-338.
PMID: 31901918

INTRODUCTION: Acute myeloid leukaemia (AML) with t(8;21)(q22;q22) producing RUNX1-RUNX1T1 rearrangement is a distinct sub-type which is usually associated with a favourable clinical outcome. Variant forms of t(8;21) are rare. Herein we describe a novel variant of t(8;21) AML in a 25-year-old pregnant woman who presented with intermittent fever.
CASE REPORT: Her peripheral smear and bone marrow aspirate showed many myeloblasts. Chromosomal study revealed t(8;22;21)(q22;q12;q22) and loss of X chromosome. Fluorescence in situ hybridization (FISH) using whole chromosome painting probes confirmed the three-way translocation involving chromosomes 8, 21 and 22. RUNX1-RUNX1T1 rearrangement was identified in FISH and reverse transcriptase polymerase chain reaction confirming the diagnosis of AML with variant t(8;21). The patient was treated with standard chemotherapy. She achieved morphological remission one month after induction chemotherapy.
DISCUSSION: Although the clinical significance of variant t(8;21) is not well delineated, the evaluation of 31 such cases suggests patients with variant t(8;21) have similar prognosis to those with classical t(8;21).

Matched MeSH terms: Translocation, Genetic/genetics
Variation in BCL2 protein expression in follicular lymphomas without t(14;18) chromosomal translocations

Masir N, Jones M, Abdul-Rahman F, Florence CS, Mason DY

Pathology, 2012 Apr;44(3):228-33.
PMID: 22406486 DOI: 10.1097/PAT.0b013e3283513fb2

The hallmark of follicular lymphoma is the t(14;18)(q32;q21) chromosomal translocations that lead to deregulation of BCL2 expression in tumour cells. However, not all cases of follicular lymphoma express BCL2, nor is the t(14;18) translocation always present. Follicular lymphomas lacking the BCL2 rearrangement are less well studied with regards to their immunohistochemical and molecular features. This study aims to investigate the BCL2 protein expression pattern in t(14;18) negative follicular lymphomas.

Matched MeSH terms: Translocation, Genetic/genetics*
Fulltext Whole-transcriptome sequencing identifies a distinct subtype of acute lymphoblastic leukemia with predominant genomic abnormalities of EP300 and CREBBP

Qian M, Zhang H, Kham SK, Liu S, Jiang C, Zhao X, et al.

Genome Res, 2017 02;27(2):185-195.
PMID: 27903646 DOI: 10.1101/gr.209163.116

Chromosomal translocations are a genomic hallmark of many hematologic malignancies. Often as initiating events, these structural abnormalities result in fusion proteins involving transcription factors important for hematopoietic differentiation and/or signaling molecules regulating cell proliferation and cell cycle. In contrast, epigenetic regulator genes are more frequently targeted by somatic sequence mutations, possibly as secondary events to further potentiate leukemogenesis. Through comprehensive whole-transcriptome sequencing of 231 children with acute lymphoblastic leukemia (ALL), we identified 58 putative functional and predominant fusion genes in 54.1% of patients (n = 125), 31 of which have not been reported previously. In particular, we described a distinct ALL subtype with a characteristic gene expression signature predominantly driven by chromosomal rearrangements of the ZNF384 gene with histone acetyltransferases EP300 and CREBBP ZNF384-rearranged ALL showed significant up-regulation of CLCF1 and BTLA expression, and ZNF384 fusion proteins consistently showed higher activity to promote transcription of these target genes relative to wild-type ZNF384 in vitro. Ectopic expression of EP300-ZNF384 and CREBBP-ZNF384 fusion altered differentiation of mouse hematopoietic stem and progenitor cells and also potentiated oncogenic transformation in vitro. EP300- and CREBBP-ZNF384 fusions resulted in loss of histone lysine acetyltransferase activity in a dominant-negative fashion, with concomitant global reduction of histone acetylation and increased sensitivity of leukemia cells to histone deacetylase inhibitors. In conclusion, our results indicate that gene fusion is a common class of genomic abnormalities in childhood ALL and that recurrent translocations involving EP300 and CREBBP may cause epigenetic deregulation with potential for therapeutic targeting.

Matched MeSH terms: Translocation, Genetic/genetics