Identification of PML–RARA rearrangement by RT-PCR and sequencing in an acute promyelocytic leukemia without t(15;17) on G-banding and FISH

Electrochemical Biosensors in the Diagnosis of Acute and Chronic Leukemias

Until now, morphological assessment with an optical or electronic microscope, fluorescence in situ hybridization, DNA sequencing, flow cytometry, polymerase chain reactions, and immunohistochemistry have been employed for leukemia identification. Nevertheless, despite their numerous different vantages, it is difficult to recognize leukemic cells correctly. Recently, the electrochemical evaluation with a nano-sensing interface seems an attractive alternative. Electrochemical biosensors measure the modification in the electrical characteristics of the nano-sensing interface, which is modified by the contact between a biological recognition element and the analyte objective. The implementation of nanosensors is founded not on single nanomaterials but rather on compilating these components efficiently. Biosensors able to identify the molecules of deoxyribonucleic acid are defined as DNA biosensors. Our review aimed to evaluate the literature on the possible use of electrochemical biosensors for identifying hematological neoplasms such as acute promyelocytic leukemia, acute lymphoblastic leukemia, and chronic myeloid leukemia. In particular, we focus our attention on using DNA electrochemical biosensors to evaluate leukemias.

Interdisciplinary Quality Improvement Led by the Molecular Pathology Laboratory Expedites Diagnosis of Acute Promyelocytic Leukemia

OBJECTIVES

Acute promyelocytic leukemia (APL) requires emergent treatment while definitive laboratory results are pending. Following the death of a patient whose diagnosis was delayed, we sought to improve our institution's workflow by using the EPIDEM (Exploration, Promotion, Implementation, Documentation, Evaluation, Modification) quality improvement model.

METHODS

APL is confirmed by identifying translocation t(15;17)(q24;q21) PML-RARA by using either molecular or cytogenetic methods on peripheral blood or bone marrow specimens. We used the EPIDEM model to decrease the turnaround time (TAT) of molecular diagnosis by improving communication and developing reflex testing. We additionally compared 32 APL cases against a control group of 18 suspected APL cases.

RESULTS

Our review of 687 multiplex polymerase chain reaction orders and 33 PML-RARA orders (January 2012 to April 2021) showed an initial TAT decrease from 4.48 days to 2.71 days (P < .0001), which further decreased to 0.64 days (P < .0001) after implementation of the PML-RARA qualitative assay. Compared with patients suspected of having APL, patients with confirmed APL had higher dimerized plasmin fragment D (P = .0145), lower fibrinogen (P ≤ .0001), and lower WBC (P ≤ .0001).

CONCLUSIONS

By using the EPIDEM model, with its emphasis on local context, culture, and resources, improved communication and workflow changes enabled us to reduce the time needed to diagnose APL to 0.64 days and identify potential locally derived screening cutoffs.

Cytogenetically cryptic PML::RARA fusion in acute promyelocytic leukemia: Testing strategies in the modern era

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Cytogenetically cryptic PML::RARA fusions is an exceedingly rare phenomenon in acute promyelocytic leukemia

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Multiple methodologies may be employed for detecting the cryptic PML::RARA fusion

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Concurrent mutations can be identified in cases of acute promyelocytic leukemia with a cryptic PML::RARA fusion; however, a unifying genomic feature remains elusive

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For cases with a high clinical suspicion of acute promyelocytic leukemia and no cytogenetic evidence of a PML::RARA fusion, complementary techniques should be employed for further analysis

Acute promyelocytic leukemia (APL) is a unique leukemia that is characterized by the PML::RARA fusion. This fusion is often detected by conventional karyotype and fluorescence in situ hybridization (FISH); however, rare cases are cryptic and require molecular techniques to identify the PML::RARA fusion. Furthermore, as the incidence of these cases is rare, analysis by a targeted next-generation sequencing (NGS) panel of myeloid associated genes has never been reported. Herein, a clinical APL case is reported where the PML::RARA fusion was detected only by reverse transcriptase-polymerase chain reaction (RT-PCR), thus underscoring the necessity of utilizing complementary techniques when suspicion for APL is present.

Identification of a new cryptic PML-RARα fusion gene without t(15;17) and biallelic CEBPA mutation in a case of acute promyelocytic leukemia: a case detected only by RT-PCR but not cytogenetics and FISH

Acute promyelocytic leukemia (APL) is characterized by the presence of promyelocytic leukemia-retinoic acid receptor α (PML-RARα) fusion gene, which is formed following the specific chromosomal translocation t(15;17)(q22;q21). However, cases with PML-RARα generated by occult t(15;17) which are negative by both cytogenetics and fluorescence in situ hybridization (FISH), are difficult to diagnose, leading to impaired treatment effectiveness. In the present study, we reported a case of a 66-year-old male patient, and bone marrow morphology, flow cytometry and cytogenetics did not support the diagnosis of APL. Molecular techniques, such as reverse-transcription polymerase chain reaction (RT-PCR), showed the existence of a cryptic PML-RARα fusion gene, and sequence analysis revealed a new variable isoform. Hotspot gene mutation analysis showed a biallelic CEBPA mutation. He received IA chemotherapy and all-trans retinoic acid (ATRA) treatment, and finally achieved complete remission. This case report provided valuable insights into the relevance of the correct identification of atypical PML-RARα fusion gene and biallelic CEBPA mutation. Moreover, combination of IA chemotherapy and ATRA treatment suggested a good clinical effect in this atypical PML-RARα.

Acute promyelocytic leukemia with a cryptic insertion of RARA into TBL1XR1

Acute promyelocytic leukemia (APL) is cytogenetically characterized by the t(15;17) (q24;q21), although cases without this translocation exist. These cases are referred to as "cryptic" or "masked" translocations. Additionally, fewer than 5% of APL cases have another partner gene fused to the RARA gene. The TBL1XR1-RARA fusion gene has recently been reported as a novel RARA-associated fusion gene. We report a case with TBL1XR1-RARA and a masked translocation that was not detected by conventional tests for RARA-associated translocations. Three-year-old girl was diagnosed with APL based morphological findings, although conventional tests for RARA-associated chimeric genes were negative. She received all-trans retinoic acid treatment, but that was not effective. She achieved a complete remission (CR) by conventional multidrug chemotherapy, but had extramedullary relapse 2 years after onset. She underwent cord blood transplantation (CBT) in her second CR and is currently alive. To investigate the underlying pathogenesis of this unique case, we performed whole-genome sequencing and found a cryptic insertion of RARA gene into the TBL1XR1 gene. The transcript of the chimeric gene, TBL1XR1-RARA, was confirmed as an in-frame fusion by RT-PCR. In conclusion, we found using next-generation sequencing (NGS) a TBL1XR1-RARA fusion in a child with variant APL without the classic karyotype. Cryptic insertion could also occur in cases other than APL with PML-RARA. Variant APL has many variants and NGS analysis should therefore be considered for APL variant cases, even for those without RARA translocation detected by conventional analysis.

t(15; 17) associated with primary myelofibrosis: a case report of an unusual clinical presentation and diagnostic dilemma

Background

primary myelofibrosis (PMF) is a myeloproliferative neoplasm which is associated with clonal molecular and cytogenetic abnormalities (CA) and varied clinical manifestations. While various CA have been previously described, t(15; 17) has not been reported in association with this condition.

Case presentation

A 69-year-old male presented with constitutional symptoms, cytopenias and bone marrow biopsy revealed immature blasts with fibrosis. Cytogenetic analysis showed a t(15;17) which initially suggested a diagnosis of acute promyelocytic leukemia (APL). However, flourescence in situ hybridization (FISH) and reverse transcriptase polymerase chain reaction (RT-PCR) studies were negative for transcripts promyelocytic leukemia (PML) gene and retinoic acid receptor alpha (RARA) or PML-RARA fusion. Along with these results, a second review of bone marrow histology, flowcytometry and the detection of a calreticulin gene (CALR) mutation helped with the correct diagnosis of PMF. Patient was then treated with ruxolitinib, a JAK (Janus kinase) 1 and 2 inhibitor, and eventually proceeded to receive a matched unrelated reduced intensity conditioning (RIC) allogeneic stem cell transplantation (ASCT) and has been doing well at the 6-month follow up.

Conclusions

Our case highlights two points, that the t(15;17) is diagnostic of Acute Promyelocytic Leukemia (APL) in most cases, there are exceptions and it can be associated with other malignancies without causing any APL like features, as noted in this case. Also, that t(15; 17) by itself is never sufficient to diagnose APL without confirmation by other methods and relying solely on cytogenetics without timely confirmatory tests can lead to risks of delay in diagnosis and appropriate management.

High-Risk Acute Promyelocytic Leukemia with Unusual T/Myeloid Immunophenotype Successfully Treated with ATRA and Arsenic Trioxide-Based Regimen

We describe two patients with acute promyelocytic leukemia (APL) with an unusual immunophenotype with co-expression of myeloperoxidase (MPO) with cytoplasmic CD3 (cCD3) representing myeloid and T-lineage differentiation. Both harbored FLT3-ITD mutations. One additionally had a deletion in the PML gene affecting the primer binding site, thus limiting measurable residual disease (MRD) analysis during follow-up. Both patients achieved durable remission with all-trans retinoic acid (ATRA) and arsenic trioxide (ATO)-based therapy, thus mitigating the need for repetitive conventional chemotherapy cycles and allogeneic stem cell transplantation. Our report highlights the complexity and challenge of diagnosis and management of APL due to the variant immunophenotype and genetics, and underscores the importance of synthesizing information from all testing modalities. The association of the unusual immunophenotype and FLT3-ITD mutation illustrates the plasticity of the hematopoietic stem cell and the pathobiology of leukemia with mixed lineage or lineage infidelity.

New nanoplatforms based on upconversion nanoparticles and single-walled carbon nanohorns for sensitive detection of acute promyelocytic leukemia

New nanoplatforms were prepared by using upconversion nanoparticles as energy donor and single-walled carbon nanohorns as energy acceptor.

Acute promyelocytic leukemia with isochromosome 17q and cryptic PML-RARA successfully treated with all-trans retinoic acid and arsenic trioxide

Acute promyelocytic leukemia (APL) is a subtype of acute leukemia that is characterized by typical morphology, bleeding events and distinct chromosomal aberrations, usually the t(15;17)(q22;q21) translocation. Approximately 9% of APL patients harbor other translocations involving chromosome 17, such as the t(11;17)(q23;q21), t(5;17)(q35;q12-21), t(11;17)(q13;q21), and der(17). All-trans retinoic acid (ATRA) and arsenic trioxide (ATO) have specific targeted activities against the PML-RARA fusion protein. The combination of ATRA and ATO is reportedly superior to chemotherapy and ATRA as induction therapy for APL. The clinical significance of non-t(15:17) APL-related aberrations is controversial, with conflicting reports regarding sensitivity to modern, targeted therapy. Isochromosome 17q (iso(17q)) is rarely associated with APL and usually occurs concurrently with the t(15:17) translocation. No published data is available regarding the efficacy of ATO-based therapy for APL patients who harbor iso(17q). We report on an APL patient with iso(17q) as the sole cytogenetic aberration and a cryptic PML-RARA transcript, who was treated with ATRA and ATO after failure of chemotherapy and achieved complete remission. To our knowledge, this is the first published report of APL associated with iso(17q) as the sole cytogenetic aberration, which was successfully treated with an ATO containing regimen.

[Acute promyelocytic leukaemia with translocations of t(15;17)(q22;q21) and rob(13;21): a case report and literatures review]

OBJECTIVE

To report an acute promyelocytic leukaemia (APL) case with translocation of rob (13;21) t(15;17) (q22;q21) and review its clinical and laboratory characteristics.

METHODS

Based on routine karyotype analysis and bone marrow morphology, we further used double color double fluorescent in situ hybridization (DCDF-FISH) and reverse transcriptase PCR (RT-PCR) to examine the patient's abnormities on cytogenetic and molecular biology, and reveal the clinical characteristics of this rare translocation also from the related literatures.

RESULTS

The clinical manifestation and bone marrow morphology examination of this patient were in accordance with pathologic feature of APL. On first visit, immunophenotyping analysis showed positive myeloid markers. Through R-banding, the patient's karyotype was confirmed as 45, XX, rob(13;21) t(15;17) (q22;q21) [6]/45, XX, rob(13;21) [14]. FISH results showed that 68.9% cells were typical t(15;17) pattern. The positive rates of fusion gene of PML-RARα detected by RT-PCR was 25.8%. Patient was treated by induction and consolidation therapy, the karyotype was 45, XX, rob(13;21 )[20] after complete remission. The positive rate of fusion gene of PML-RARα by FISH and its level were 2.5% and 0.003% respectively.

CONCLUSION

APL with rob (13;21) t(15;17) (q22;q21) was very rare, which was accorded with clinical and laboratory characteristics of APL. The value of chromosome abnormality as a prognostic marker in APL needs to be further observed..

Detection of promyelocytic leukemia/retinoic acid receptor α (PML/RARα) fusion gene with functionalized graphene oxide

An attempt was made to use functionalized graphene oxide (GO) to detect the Promyelocytic leukemia/Retinoic acid receptor α fusion gene (PML/RARα fusion gene), a marker gene of acute promyelocytic leukemia. The functionalized GO was prepared by chemical exfoliation method, followed by a polyethylene glycol grafting. It is found that the functionalized GO can selectively adsorb the fluorescein isothiocyanate (FITC)-labeled single-stranded DNA probe and quench its fluorescence. The probe can be displaced by the PML/RARα fusion gene to restore the fluorescence, which can be detected by laser confocal microscopy and flow cytometry. These can be used to detect the presence of the PML/RARα fusion gene. This detection method is verified to be fast, simple and reliable.

Sequence-specific electrochemical detection of double-strand PCR amplicons of PML/RARα fusion gene in acute promyelocytic leukemia

A novel electrochemical method for the sequence-specific detection of double-stranded polymerase chain reaction (PCR) products of PML/RARα fusion gene in acute promyelocytic leukemia (APL) was described in detail. Based on a "sandwich" sensing mode involving a pair of locked nucleic acids probes (capture probe and reporter probe), this DNA sensor exhibited excellent selectivity and specificity. The direct and quantitative analysis of double-stranded complementary was firstly performed by our sensor without the use of alkali, helicase enzymes, or denaturants. Finally, combining PCR technique with electrochemical detection scheme, PCR amplicons (191 bp) of the PML/RARα fusion gene were obtained and rapidly identified with a low detection limit of 79 fmol in the 100-μL hybridization system. The results clearly showed the power of sensor as a promising tool for the sensitive, specific, and portable detection of APL and other diseases.

Rapid detection of prognostically significant fusion transcripts in acute leukemia using simplified multiplex reverse transcription polymerase chain reaction

Multiplex reverse transcription polymerase chain reaction (mRT-PCR) has recently emerged as an alternative to cytogenetics. We designed and used simplified mRT-PCR system as a molecular screen for acute leukemia. Fifteen fusion transcripts were included: BCR-ABL1, PML-RARA, ZBTB16-RARA, RUNX1-RUNX1T1, CBFB-MYH11, DEK-NUP214, TCF3-PBX1, ETV6-RUNX1, MLL-AFF1, MLL-MLLT4, MLL-MLLT3, MLL-MLLT10, MLL-ELL, MLL-MLLT1, and MLL-MLLT6. A total of 121 diagnostic acute leukemia specimens were studied, comparing the mRT-PCR system with standard cytogenetics. Fifty-six cases (46.3%) had fusion transcripts revealed by our mRT-PCR assay. The concordance rate between mRT-PCR and cytogenetics was 91.7%. However, false negative results were found in three cases who have inv(16), t(4;11) or t(11;19)(q23;p13.1), respectively. Seven cryptic translocations including ETV6-RUNX1, MLL-MLLT3, MLL-MLLT4, and PML-RARA were detected. This mRT-PCR assay is a useful screening tool in acute leukemia because it provides rapid and reliable detection of clinically important chimeric transcripts. In addition, cryptic translocations provide additional genetic information that could be clinically useful.

Multiple cranial neuropathy and intracranial hypertension associated with all-trans retinoic acid treatment in a young adult patient with acute promyelocytic leukemia

All-trans retinoic acid (ATRA) induces complete remission in 64-100 % of patients with acute promyelocytic leukemia (APL), and is considered to be a safe agent. Pseudotumor cerebri is a neurological side effect of ATRA reported in pediatric patients, and which is characterized by raised cerebrospinal fluid pressure in the absence of any intracranial pathology or secondary causes of intracranial hypertension. Involvement of cranial nerves other than II and VI is very uncommon in idiopathic intracranial hypertension (IIH); peripheral facial nerve palsy is exceptional and has rarely been described in the context of treatment with ATRA. We describe the case of a 15-year-old female patient with APL who developed an IIH and involvement of cranial nerves (bilateral papilledema, left facial and right sixth nerves) after receiving induction therapy including ATRA. Viral infections and other causes of secondary cranial nerve lesions were excluded. Symptoms completely subsided with the temporary withdrawal of ATRA and did not recur after reintroducing the drug. To date, the patient has managed to receive the treatment as per protocol. In conclusion, we report an atypical presentation of IIH that merits consideration, especially with respect to young patients with APL receiving ATRA; our most important observation is that the drug could be safely reintroduced once the symptoms had resolved.

Interstitial insertion of RARα gene into PML gene in a patient with acute promyelocytic leukemia (APL) lacking the classic t(15;17)

The diagnosis of APL is based on clinical and morphological tests though the final diagnosis is at the molecular level. An accurate diagnosis is important as it mandates targeted therapy to improve survival. We report a case of APL without t(15;17) in conventional cytogenetic study and with initially negative fluorescence in situ hybridization (FISH) study on cells in interphase. Reverse transcription polymerase chain reaction (RT-PCR) for the promyelocytic/retinoic acid receptor alpha gene (PML/RARα) fusion oncogene proved the clinical diagnosis as well as FISH study on cells in metaphase. The cause was a cryptic translocation of the RARα gene into PML. We reviewed 36 additional cases of APL diagnosed in our hospital since 1992. This was the only case that failed to show t(15;17) in cytogenetics. However, three cases with t(15;17) in cytogenetics had negative RT-PCR for PML/RARα. Our case emphasizes that cytogenetics, FISH and RT-PCR studies are complementary studies for the molecular diagnosis of APL.

Design of a sandwich-mode amperometric biosensor for detection of PML/RARα fusion gene using locked nucleic acids on gold electrode

In this study, a novel DNA electrochemical probe (locked nucleic acid, LNA) was designed and involved in constructing an electrochemical DNA biosensor for detection of promyelocytic leukemia/retinoic acid receptor alpha (PML/RARα) fusion gene in acute promyelocytic leukemia for the first time. This biosensor was based on a 'sandwich' sensing mode, which involved a pair of LNA probes (capture probe immobilized at electrode surface and biotinyl reporter probe as an affinity tag for streptavidin-horseradish peroxidase (streptavidin-HRP). Since biotin can be connected with streptavidin-HRP, this biosensor offered an enzymatically amplified electrochemical current signal for the detection of target DNA. In the simple hybridization system, DNA fragment with its complementary DNA fragment was evidenced by amperometric detection, with a detection limit of 74 fM and a linear response range of 0.1-10 pM for synthetic PML/RARα fusion gene in acute promyelocytic leukemia (APL). Otherwise, the biosensor showed an excellent specificity to distinguish the complementary sequence and different mismatch sequences. The new pattern also exhibited high sensitivity and selectivity in mixed hybridization system.