Acute myeloid leukemia with a novel AKAP9::PDGFRA fusion transformed from essential thrombocythemia: A case report and mini review.

Acute myeloid leukemia (AML) is a heterogeneous hematological malignancy associated with various combinations of gene mutations, epigenetic abnormalities, and chromosome rearrangement-related gene fusions. Despite the significant degree of heterogeneity in its pathogenesis, many gene fusions and point mutations are recurrent in AML and have been employed in risk stratification over the last several decades. Gene fusions have long been recognized for understanding tumorigenesis and their proven roles in clinical diagnosis and targeted therapies. Advances in DNA sequencing technologies and computational biology have contributed significantly to the detection of known fusion genes as well as for the discovery of novel ones. Several recurring gene fusions in AML have been linked to prognosis, treatment response, and disease progression. In this report, we present a case with a long history of essential thrombocythemia and hallmark CALR mutation transforming to AML characterized by a previously unreported AKAP9::PDGFRA fusion gene. We propose mechanisms by which this fusion may contribute to the pathogenesis of AML and its potential as a molecular target for tyrosine kinase inhibitors.

Isochromosome 7p, i(7)(p10): A rare AML, myelodysplasia-related entity.

We describe genomic findings in an AML case with isochromosome 7p, i(7)(p10), in which SNP array analysis uncovered an additional 7.07-Mb 20q deletion not detected by karyotyping. Several AML cases with i(7)(p10) as an isolated cytogenetic finding have been previously reported. Based on consequent loss of 7q, we propose that AML with i(7)(p10) represents a distinct entity belonging in the WHO group -7/7q-, which represents one of the genetic abnormalities defining AML, myelodysplasia-related. Additionally, the focal del(20q) identified here adds support for a specific common region of deletion in 20q in myeloid malignancies, implicating a small number of candidate genes.

PDJ amplicon in triple negative breast cancer.

Amplification of chromosome 9p24.1 targeting PD-L1, PD-L2, and JAK2 (PDJ amplicon) is present in subsets of triple negative breast cancers (TNBCs) and is associated with poor clinical outcomes. However, the prevalence of PDJ+ TNBCs varies extensively across studies applying different methods for interrogating samples of interest. To rigorously assess the prevalence of PDJ amplicons in TNBC, its prognostic value and whether it is enriched by chemotherapy, we interrogated 360 TNBC samples including 74 surgical resections from patients treated in the neoadjuvant setting, and tissue microarrays (TMAs) with 31 cases from African American women and 255 resected non-metastatic cases, with a 3 color fluorescence in situ hybridization (FISH) assay targeting the 9p24.1 PDJ amplicon, 9q24.3, and 9q34.1. Samples with mean PDJ signal of > 4.5 copies, and ratios of PDJ/9q24 ≥ 2 and/or PDJ/9q34.1 ≥ 2 were called amplified (PDJ+). Correlative analyses included the association of tumor infiltrating lymphocytes (TILs) with PDJ amplicons in TNBCs. In addition, we investigated intratumor copy number of PDJ amplicons in PDJ+ and PDJ- TNBCs. Matched pre- and post-neoadjuvant treatment biopsies were available from patients (n = 6) to evaluate the effects of therapy on PDJ status. Our study provides a rigorous analysis of the prevalence, distribution, and clinical correlatives of the PDJ amplicon in TNBC.

Coexistence of neocentromeric marker 3q and trisomy 3 in two different tissues in a 3-year-old boy with peripheral T-cell lymphoma: support for a gene dosage effect hypothesis.

A very small supernumerary de novo marker chromosome was ascertained during cytogenetic diagnosis of a 3 1/2-year-old boy with peripheral T-cell lymphoma, unspecified. The marker, which was C-band and alpha-satellite DNA negative, was identified in the pleural effusion and involved cervical lymph node whereas the involved bone marrow cells had trisomy 3 as a clone. The neocentromere marker was characterized by multiple probes demonstrating an inversion duplication of the distal portion of chromosome 3q involving the BCL6 gene. Whole or partial trisomy 3q represents one of the most recurrent chromosomal abnormalities occurring in T-cell lymphomas, suggesting that the 3q contains a critical region for the pathogenesis of T-cell lymphoma. Our present case showed that the critical region may reside within the neocentromere marker 3q27~q29 in this case in particular and revealed a different mechanism in increasing gene dosage rather than gene disruption. In addition, this type of neocentromere is one most often reported in constitutional cases. Here, we report its presence in cancer for the first time.