The Nijmegen Modification of the Bethesda Assay for Factor VIII:C Inhibitors: Improved Specificity and Reliability

Antibodies against factor VIII coagulant activity can appear in haemophiliacs who are treated with factor VIII preparations but also spontaneously in non-haemophiliacs. The Bethesda assay is the most commonly used method to detect these antibodies, but it lacks specificity especially in the lower range resulting in unreliable data.

Two modifications are proposed and tested to resolve the imperfections:

1. Buffering the normal plasma used in the assay- and control mixture with 0.1 M imidazole to pH 7.4.

Replacing the imidazole buffer in the control mixture by immunodepleted factor VIII deficient plasma.

These modifications allow better discrimination between positive and negative samples and improve reliability.

Chemically triggered drug release from an antibody-drug conjugate leads to potent antitumour activity in mice

Current antibody-drug conjugates (ADCs) target internalising receptors on cancer cells leading to intracellular drug release. Typically, only a subset of patients with solid tumours has sufficient expression of such a receptor, while there are suitable non-internalising receptors and stroma targets. Here, we demonstrate potent therapy in murine tumour models using a non-internalising ADC that releases its drugs upon a click reaction with a chemical activator, which is administered in a second step. This was enabled by the development of a diabody-based ADC with a high tumour uptake and very low retention in healthy tissues, allowing systemic administration of the activator 2 days later, leading to efficient and selective activation throughout the tumour. In contrast, the analogous ADC comprising the protease-cleavable linker used in the FDA approved ADC Adcetris is not effective in these tumour models. This first-in-class ADC holds promise for a broader applicability of ADCs across patient populations.

Current antibody-drug conjugates (ADCs) target internalising receptors on cancer cells. Here, the authors report the development and in vivo validation of a non-internalising ADC with the capacity to target cancer cells and release its therapeutic cargo extracellularly via a chemical trigger.

A functional peptidyl-tRNA hydrolase, ICT1, has been recruited into the human mitochondrial ribosome

Bioinformatic analysis classifies the human protein encoded by immature colon carcinoma transcript-1 (ICT1) as one of a family of four putative mitochondrial translation release factors. However, this has not been supported by any experimental evidence. As only a single member of this family, mtRF1a, is required to terminate the synthesis of all 13 mitochondrially encoded polypeptides, the true physiological function of ICT1 was unclear. Here, we report that ICT1 is an essential mitochondrial protein, but unlike the other family members that are matrix-soluble, ICT1 has become an integral component of the human mitoribosome. Release-factor assays show that although ICT1 has retained its ribosome-dependent PTH activity, this is codon-independent; consistent with its loss of both domains that promote codon recognition in class-I release factors. Mutation of the GGQ domain common to ribosome-dependent PTHs causes a loss of activity in vitro and, crucially, a loss of cell viability, in vivo. We suggest that ICT1 may be essential for hydrolysis of prematurely terminated peptidyl-tRNA moieties in stalled mitoribosomes.

Mutations in NDUFAF3 (C3ORF60), encoding an NDUFAF4 (C6ORF66)-interacting complex I assembly protein, cause fatal neonatal mitochondrial disease

Mitochondrial complex I deficiency is the most prevalent and least understood disorder of the oxidative phosphorylation system. The genetic cause of many cases of isolated complex I deficiency is unknown because of insufficient understanding of the complex I assembly process and the factors involved. We performed homozygosity mapping and gene sequencing to identify the genetic defect in five complex I-deficient patients from three different families. All patients harbored mutations in the NDUFAF3 (C3ORF60) gene, of which the pathogenic nature was assessed by NDUFAF3-GFP baculovirus complementation in fibroblasts. We found that NDUFAF3 is a genuine mitochondrial complex I assembly protein that interacts with complex I subunits. Furthermore, we show that NDUFAF3 tightly interacts with NDUFAF4 (C6ORF66), a protein previously implicated in complex I deficiency. Additional gene conservation analysis links NDUFAF3 to bacterial-membrane-insertion gene cluster SecF/SecD/YajC and to C8ORF38, also implicated in complex I deficiency. These data not only show that NDUFAF3 mutations cause complex I deficiency but also relate different complex I disease genes by the close cooperation of their encoded proteins during the assembly process.

Effects of day care on the development of cognitive abilities in 8-year-olds: a longitudinal study

In Göteborg, Sweden, 146 children (72 girls) were enrolled in a longitudinal study when they averaged 16 months of age. None of the children had experienced regular out-of-home care yet, but within 3 months, 54 entered center care and 33 entered family day care. Quality of home and out-of-home care environments, child temperament, and the development of verbal abilities were assessed regularly during preschool years. When they were 8 years old (2nd grade), cognitive ability tests were administered to the 123 children (65 girls) still in the study. Tested ability was related to the number of months children had spent in center-based day care before 3.5 years of age. Child care quality predicted cognitive abilities among children who had spent at least 36 months in out-of-home care during their preschool years. Both tested and rated cognitive abilities in 2nd grade were related to earlier measures of verbal ability and to paternal involvement during preschool years.

The human mitochondrial ribosome recycling factor is essential for cell viability

The molecular mechanism of human mitochondrial translation has yet to be fully described. We are particularly interested in understanding the process of translational termination and ribosome recycling in the mitochondrion. Several candidates have been implicated, for which subcellular localization and characterization have not been reported. Here, we show that the putative mitochondrial recycling factor, mtRRF, is indeed a mitochondrial protein. Expression of human mtRRF in fission yeast devoid of endogenous mitochondrial recycling factor suppresses the respiratory phenotype. Further, human mtRRF is able to associate with Escherichia coli ribosomes in vitro and can associate with mitoribosomes in vivo. Depletion of mtRRF in human cell lines is lethal, initially causing profound mitochondrial dysmorphism, aggregation of mitoribosomes, elevated mitochondrial superoxide production and eventual loss of OXPHOS complexes. Finally, mtRRF was shown to co-immunoprecipitate a large number of mitoribosomal proteins attached to other mitochondrial proteins, including putative members of the mitochondrial nucleoid.

Relationship of plasma cholesteryl ester transfer protein to HDL cholesterol. Studies in normotriglyceridemia and moderate hypertriglyceridemia

To evaluate the independent effect of cholesteryl ester transfer protein (CETP) on HDL concentrations in humans, we measured lipids, lipoproteins, postprandial lipemia after an oral fat load, CETP mass, and the activities of CETP, lipoprotein lipase (LPL), and hepatic lipase in 16 healthy, normotriglyceridemic men and in 23 men with moderate, primary hypertriglyceridemia on an American Heart Association Step I diet. Fasting triglycerides and postprandial lipemia were increased and HDL cholesterol (HDL-C) was decreased in hypertriglyceridemic men compared with control subjects (P < .001). In the normotriglyceridemic group, CETP mass (P < .001) and activity (P < .005) were directly related to LPL activity After statistical adjustment for this close association, no significant relationship of CETP to HDL-C independent of LPL activity could be demonstrated in the normotriglyceridemic subjects. In contrast, CETP was unrelated to LPL activity in the hypertriglyceridemic subjects, but CETP concentrations showed a close inverse relationship to HDL-C (r = -.504, P = .014). Structural equation modeling of the association structures between HDL and fasting and postprandial triglycerides, endothelial lipases, and CETP in both groups indicated that the overall regression models for the two groups differed (P < .05). Specifically, the associations between CETP mass and activity and HDL-C differed between both groups (both P < .01). We conclude that high-normal CETP levels lower HDL-C in nonsmoking, nonobese men with moderate, primary hypertriglyceridemia on a hypolipidemic diet, but not in healthy, normotriglyceridemic men on an unrestricted diet. Thus, variation in CETP plasma concentrations may contribute to the high-triglyceride, low-HDL phenotype.

Identification of RUNX1/AML1 as a classical tumor suppressor gene

Based on our previous results indicating the presence of a tumor suppressor gene (TSG), chromosome 21 was analysed for loss of heterozygosity (LOH) in 18 patients with acute myeloid leukemia (17, AML-M0; one, AML-M1). Allelotyping at polymorphic loci was performed on purified material, allowing unequivocal detection of allelic loss and homozygous deletions. Six AML-M0 patients shared a common region of LOH harboring a single gene: RUNX1 (AML1), the most frequent site of translocations in acute leukemia and a well-known fusion oncogene. Fluorescence in situ hybridization allowed the identification of deletions with breakpoints within RUNX1 in two patients as the cause of LOH. In the four others the LOH pattern and the presence of two karyotypically normal chromosomes 21 were in line with mitotic recombination. Further molecular and cytogenetic analyses showed that this caused homozygosity of primary RUNX1 mutations: two point mutations, a partial deletion and, most significantly, a complete deletion of RUNX1. These findings identify RUNX1 as a classical TSG: both alleles are mutated or absent in cancer cells from four of the 17 AML-M0 patients examined. In contrast to AML-M0, the AML-M1 patient was trisomic for chromosome 21 and has two mutated and one normal RUNX1 allele, suggesting that the order of mutagenic events leading to leukemia may influence the predominant tumor type.

Bone marrow repopulation capacity after transplantation of lymphocyte-depleted allogeneic bone marrow using counterflow centrifugation

Bone marrow from six allogeneic HLA-matched and MCL nonreactive siblings was fractionated by means of isopycnic flotation centrifugation and subsequent counterflow centrifugation. The low density fraction (d less than or equal to 1.070 g/ml) obtained by IFC contained 20% of the nucleated cells and more than 90% of the myeloid and erythroid progenitors. The putative stem cell fraction obtained by CC showed a satisfactory recovery (88%) of the CFU-GM and BFU-E and only 3.5% of the original number of T lymphocytes. Bone marrow repopulation capacity was not impaired in comparison with a comparable group of patients. Despite the average high age of this group (29.6 years), only one of the four evaluable patients developed graft-versus-host disease.

A low but functionally significant MDR1 expression protects primitive haemopoietic progenitor cells from anthracycline toxicity

Pgp is expressed on normal haemopoietic progenitor cells. The significance of the efflux pump in protecting normal progenitors for anthracycline toxicity is not defined and is the subject of this study. Pgp was measured in CD34+ progenitors with a rhodamine efflux assay. A high efflux, modulated by verapamil, was only found in a distinct subpopulation (20-30%). Pgp measured by the monoclonal antibody antibody (MoAb) MRK-16 was low in the rhodamine dull, but significantly (P < 0.04) higher than in the rhodamine bright cells. Reverse transcriptase polymerase chain reaction (RT-PCR) of MDR1 mRNA showed a very weak signal in both populations. In a single-cell clonogenic assay, rhodamine dull cells appeared less sensitive to anthracyclines (IC50 daunorubicin 0.005 microg/ml; adriamycin 0.03 microg/ml) compared to rhodamine bright cells (IC50 daunorubicin 0.0025 microg/ml; adriamycin 0.01 microg/ml). Furthermore, verapamil significantly (P < 0.05) potentiated anthracycline toxicity only in the rhodamine dull cells, proving its Pgp-specific modulating effect. Rhodamine dull cells gave larger and more mixed colonies compatible with a more primitive origin. Although detection with MoAbs and RT-PCR revealed a low Pgp level, functionally this Pgp appeared to be very important in protecting primitive progenitors against anthracycline toxicity. This protection can be jeopardized by administration of Pgp modulators.

Determination of 1-beta-D-arabinofuranosylcytosine and 1-beta-D-arabinofuranosyluracil in human plasma by high-performance liquid chromatography

A method is described for the determination of 1-beta-D-arabinofuranosylcytosine (Ara-C) and its metabolite 1-beta-D-arabinofuranosyluracil (Ara-U) in human plasma. After deproteinization of the plasma sample, separation is performed by reversed-phase liquid chromatography. For Ara-C concentrations exceeding 0.05 mg/l and for Ara-U concentrations exceeding 1 mg/l, injection volumes of 100 microliter are applied. For lower concentrations an injection volume of 500 microliter is used. Ara-C is detected at 280 nm with a lowest detection limit of 0.002 mg/l in plasma. Ara-U is detected at 264 nm with a lowest detection limit varying from 0.01 to 0.1 mg/l in plasma. This variation is caused by an unknown substance with the same elution properties as Ara-U and which appears to be present in plasma in variable concentrations. The coefficient of variation of the whole procedure is about 6% for Ara-C concentrations above 0.005 mg/l and for Ara-U concentrations above 0.1 mg/l. For lower concentrations the coefficient of variation is about 14%.

Implementation of a multi-institutional diffuse intrinsic pontine glioma autopsy protocol and characterization of a primary cell culture

AIMS

Diffuse intrinsic pontine glioma (DIPG) is a fatal paediatric malignancy. Tumour resection is not possible without serious morbidity and biopsies are rarely performed. The resulting lack of primary DIPG material has made preclinical research practically impossible and has hindered the development of new therapies for this disease. The aim of the current study was to address the lack of primary DIPG material and preclinical models by developing a multi-institutional autopsy protocol.

METHODS

An autopsy protocol was implemented in the Netherlands to obtain tumour material within a brief post mortem interval. A team of neuropathologists and researchers was available at any time to perform the autopsy and process the material harvested. Whole brain autopsy was performed and primary DIPG material and healthy tissue were collected from all affected brain areas. Finally, the study included systematic evaluation by parents.

RESULTS

Five autopsies were performed. The mean time interval between death and time of autopsy was 3 h (range 2-4). All tumours were graded as glioblastoma. None of the parents regretted their choice to participate, and they all derived comfort in donating tissue of their child in the hope to help future DIPG patients. In addition, we developed and characterized one of the first DIPG cell cultures from post mortem material.

CONCLUSION

Here we show that obtaining post mortem DIPG tumour tissue for research purposes is feasible with short delay, and that the autopsy procedure is satisfying for participating parents and can be suitable for the development of preclinical DIPG models.

In-vitro studies on phosphorylation and dephosphorylation of cytosine arabinoside in human leukemic cells

The cytotoxic effect of cytosine arabinoside (ara-C) depends on the capacity of cells to form and retain intracellularly the phosphorylated metabolite cytosine arabinoside triphosphate (ara-CTP). In this study accumulation and cellular retention of ara-CTP have been measured in vitro in the bone marrow cells of 69 patients with acute leukemia. Cells were incubated with 3H-ara-C and the amount of ara-CTP formed was determined after separation of the nucleotides by thin-layer chromatography. Phosphorylation of ara-C to ara-CTP appeared to be a saturable process. The Km-equivalents varied between 1.1 and 16.2 microM ara-C. Maximal ara-CTP formation ranged from 12 to 125 pmol ara-CTP/10(6) cells in 30 min. The phosphorylation activity did not correlate with the percentage of S-phase cells. The intracellular half-life time of ara-CTP measured in vitro ranged from 53 to 210 min. Phosphorylation of ara-C was comparable in patients with acute myeloid leukemia (n = 51) and in patients with acute lymphoblastic leukemia (n = 18). Ara-CTP elimination appeared slower in lymphoblasts than in myeloblasts. The average intracellular ara-CTP level in relapsed patients (n = 34) appeared higher than in previously untreated patients (n = 52). The less favourable outcome of second remission induction therapy with conventional doses of ara-C compared to the first remission induction treatment is not explained by an alteration in the intracellular metabolism of ara-C.

O-glycosylation disorders pave the road for understanding the complex human O-glycosylation machinery

Over 100 human Congenital Disorders of Glycosylation (CDG) have been described. Of these, about 30% reside in the O-glycosylation pathway. O-glycosylation disorders are characterized by a high phenotypic variability, reflecting the large diversity of O-glycan structures. In contrast to N-glycosylation disorders, a generic biochemical screening test is lacking, which limits the identification of novel O-glycosylation disorders. The emergence of next generation sequencing (NGS) and O-glycoproteomics technologies have changed this situation, resulting in significant progress to link disease phenotypes with underlying biochemical mechanisms. Here, we review the current knowledge on O-glycosylation disorders, and discuss the biochemical lessons that we can learn on 1) novel glycosyltransferases and metabolic pathways, 2) tissue-specific O-glycosylation mechanisms, 3) O-glycosylation targets and 4) structure-function relationships. Additionally, we provide an outlook on how genetic disorders, O-glycoproteomics and biochemical methods can be combined to answer fundamental questions regarding O-glycan synthesis, structure and function.

Medical oncology patients' preferences with regard to health care: development of a patient-driven questionnaire

BACKGROUND

To improve quality of care for cancer patients, it is important to have an insight on the patient's view on health care and on their specific wishes, needs and preferences, without restriction and without influence of researchers and health care providers. The aim of this study was to develop a questionnaire assessing medical oncology patients' preferences for health care based on their own input.

PATIENTS AND METHODS

Items were generated using 10 focus group interviews with 51 cancer patients. A preliminary questionnaire was handed out to 681 patients of seven Dutch departments of medical oncology. Explorative factor analysis was carried out on the 386 returned questionnaires (response 57%).

RESULTS

Focus group interviews resulted in a preliminary questionnaire containing 136 items. Explorative factor analysis resulted in a definitive questionnaire containing 123 items (21 scales and eight single items). Patients rated expertise, safety, performance and attitude of physicians and nurses as the most important issues in cancer care.

CONCLUSION

This questionnaire may be used to assess preferences of cancer patients and to come to a tailored approach of health care that meets patients' wishes and needs.

Improved flow cytometry of cellular DNA and RNA by on-line reagent addition

Acridine orange (AO) staining enables flow cytometric measurement of cellular DNA and RNA. With the conventional procedure, red and green fluorescence intensities alter considerably in time, affecting the reliability and reproducibility of the results. A standardized simple technique of AO staining is described that keeps the time between addition of detergent and AO and the subsequent measurement constant. Measurements by means of this on-line method appear to be much more reproducible in comparison to those obtained using the conventional procedure.

Managing unsolicited findings in genomics: A qualitative interview study with cancer patients

OBJECTIVE

Next-generation sequencing (NGS) is increasingly being employed in the context of personalized cancer treatment. Anticipating unsolicited findings that may arise during a NGS procedure is a key consideration; however, little is known about cancer patients' intentions, needs, and preferences concerning the return of unsolicited findings.

METHODS

A qualitative design using individual semi-structured interviews with 24 cancer patients was utilized to explore patients' decisions on whether to receive unsolicited findings from NGS. These interviews were subsequently analyzed using the constant comparative method to develop codes and themes.

RESULTS

We identified 4 interrelated themes that emerged in the context of the return of unsolicited findings. First, we describe how cancer patients expressed a strong need to control their lives. Second, we show the importance of family dynamics. Third, the NGS procedure regarding unsolicited findings is perceived as cognitively complex, and fourth, the procedure is also considered emotionally complex.

CONCLUSIONS

The results of our study contribute to a better understanding of what cancer patients consider important and what may motivate and influence them when making decisions on the disclosure of unsolicited findings following NGS. We show how Joel Feinberg's classification of autonomy may help clinicians to better understand cancer patients' desire for autonomous decision making while also acknowledging the emotional and cognitive difficulties regarding the disclosure of unsolicited findings. These insights could be helpful for clinicians to guide patients through this complex process.

A novel chromosomal translocation t(3;5)(q12;p15.3) and loss of heterozygosity on chromosome 22 in a multifocal follicular variant of papillary thyroid carcinoma presenting with skin metastases

Classic genetic rearrangements in papillary carcinoma of the thyroid involve the RET- or TRK proto-oncogenes. We report a novel chromosomal translocation t(3;5)(q12;p15.3), confirmed by fluorescence in situ hybridization, in a multifocal follicular variant of a papillary carcinoma of the thyroid in a 79-year-old woman, with skin metastases as a presenting symptom. Three years earlier, another cutaneous metastasis on her scalp was misdiagnosed as hidradenoma. Four tumour foci were recognized in the thyroid, two with a follicular variant of papillary carcinoma. To detect loss of heterozygosity, 14 chromosomes were investigated with 59 microsatellite markers. A clonal relationship was detected between the two foci of tumour in the thyroid gland containing follicular variant of papillary carcinoma and one of the skin lesions tested, all demonstrating loss of heterozygosity (LOH) in the same region of chromosome 22. Based on earlier reports, the low rate of LOH detected is in agreement with the diagnosis papillary carcinoma of the thyroid. Whole body scintigraphy performed after ablative therapy with radioiodine revealed multiple metastases in the lungs and skeleton. After repeated radioiodine therapy, thyroglobulin under thyroxine suppression became undetectable and post-therapeutic scintigraphy revealed important regression of metastases.

Effects of day care on the development of cognitive abilities in 8-year-olds: a longitudinal study

In Göteborg, Sweden, 146 children (72 girls) were enrolled in a longitudinal study when they averaged 16 months of age. None of the children had experienced regular out-of-home care yet, but within 3 months, 54 entered center care and 33 entered family day care. Quality of home and out-of-home care environments, child temperament, and the development of verbal abilities were assessed regularly during preschool years. When they were 8 years old (2nd grade), cognitive ability tests were administered to the 123 children (65 girls) still in the study. Tested ability was related to the number of months children had spent in center-based day care before 3.5 years of age. Child care quality predicted cognitive abilities among children who had spent at least 36 months in out-of-home care during their preschool years. Both tested and rated cognitive abilities in 2nd grade were related to earlier measures of verbal ability and to paternal involvement during preschool years.

Genome wide molecular analysis of minimally differentiated acute myeloid leukemia

BACKGROUND

Minimally differentiated acute myeloid leukemia is heterogeneous in karyotype and is defined by immature morphological and molecular characteristics. This originally French-American-British classification is still used in the new World Health Organization classification when other criteria are not met. Apart from RUNX1 mutation, no characteristic molecular aberrations are recognized.

DESIGN AND METHODS

We performed whole genome single nucleotide polymorphism analysis and extensive molecular analysis in a cohort of 52 patients with minimally differentiated acute myeloid leukemia.

RESULTS

Many recurring and potentially relevant regions of loss of heterozygosity were revealed. These point towards a variety of candidate genes that could contribute to the pathogenesis of minimally differentiated acute myeloid leukemia, including the tumor suppressor genes TP53 and NF1, and reinforced the importance of RUNX1 in this leukemia. Furthermore, for the first time in this minimally differentiated form of leukemia we detected mutations in the transactivation domain of RUNX1. Mutations in other acute myeloid leukemia associated transcriptions factors were infrequent. In contrast, FLT3, RAS, PTPN11 and JAK2 were often mutated. Irrespective of the RUNX1 mutation status, our results show that RAS signaling is the most important pathway for proliferation in minimally differentiated acute myeloid leukemia. Importantly, we found that high terminal deoxynucleotidyl transferase expression is closely associated with RUNX1 mutation, which could allow an easier diagnosis of RUNX1 mutation in this hematologic malignancy.

CONCLUSIONS

Our results suggest that in patients without RUNX1 mutation, several other molecular aberrations, separately or in combination, contribute to a common minimally differentiated phenotype.

Impact of integration of clinical and outpatient units on cancer patient satisfaction

OBJECTIVE

There is an ongoing drive to measure and improve quality of care. Donabedians' quality framework with structure, process and outcome domains provides a useful hold to examine quality of care. The aim of this study was to address the effect of an intervention in hospital structure (integration of three units into one) with the purpose of improving processes (increase meeting, cooperation and communication between professionals and patients) and its effect on the outcome (cancer patient satisfaction).

DESIGN

Pre-test-post-test.

SETTING

University Medical Center Utrecht, The Netherlands, Department of Medical Oncology.

PARTICIPANTS

Cancer patients (n = 174, n = 97).

INTERVENTIONS

Physical integration by bringing separately located units (outpatient clinic, day-care clinic, clinical ward) together in one wing of the hospital and adjustments in communication and coordination structures.

MAIN OUTCOME MEASURE

Patient satisfaction questionnaire.

RESULTS

Satisfaction with care improved for six scales (27%) after integration. Effect sizes (ESs) ranged from 0.36 to 0.80, indicating a small to moderate effect. The most important improvement was found at the day-care clinic on aspects like 'the degree in which the nurses were informed about a patients situation', 'privacy', 'interior design', 'quality of hospital equipment', 'sanitary supplies' and 'waiting periods'. With regard to continuity and coordination of care, satisfaction increased for five items (28% of items concerning continuity and coordination of care). ESs ranged from 0.42 to 0.75.

CONCLUSIONS

Integration of three oncology units into one unit had a positive impact on care delivery processes and resulted in improved patient satisfaction concerning care and treatment.

Genomic amplification of MYC as double minutes in a patient with APL-like leukemia

BACKGROUND

Acute promyelocytic leukemia (APL) is a subtype of acute myeloid leukemia (AML) characterized by a PML-RARA fusion due to a translocation t(15;17). Its sensitivity to treatment with all-trans retinoic acid (ATRA), which causes differentiation of the abnormal promyelocytes, combined with anthracycline based chemotherapy makes it the best curable subtype of acute myeloid leukemia. A rapid and accurate diagnosis is needed in the first place to prevent (more) bleeding problems. Here we present a patient with a leukemia with an APL-like morphology but no detectable PML-RARA fusion, as demonstrated by RT-PCR and cytogenetic analysis.

RESULTS

Unexpectedly, karyotyping revealed numerous double minutes (dmins). Fluorescence in situ hybridization (FISH) with DNA probes specific for the MYC-region showed the presence of multiple MYC amplicons. SNP-array analysis uncovered amplification of the 8q24.13-q24.21 region, including the MYC-gene, flanked by deletions in 8q24.13 and 8q24.21-q24.22, and a homozygous deletion in 9p21.3, flanked by heterozygous deletions in the same chromosome region.

CONCLUSIONS

The diagnosis was revised to AML, not otherwise specified (AML, NOS) and therefore therapy with ATRA was discontinued.