Unbalanced X;Y translocations carrying SRY in prenatal settings: Clinical, molecular, and cytogenetic analysis of three cases

BACKGROUND

Generally, the translocation of SRY onto one of the X chromosomes leads to 46, XX testicular disorders of sex development, a relatively rare condition characterized by the presence of testicular tissue with a 46, XX karyotype. Three prenatal cases of unbalanced X; Y translocation carrying SRY were identified in this study.

METHODS

Structural variants were confirmed using single nucleotide polymorphism array and chromosomal karyotyping. X chromosome inactivation (XCI) was also analyzed. Detailed clinical features of the three cases were collected.

RESULTS

We identified two fetuses with maternal inherited unbalanced X; Y translocations carrying SRY and skewed XCI presenting with normal female external genitalia, and one fetus with de novo 46, XX (SRY+) and random XCI manifested male phenotypic external genitalia.

CONCLUSION

This study reports that cases with unbalanced X; Y translocations carrying SRY manifested a normal female external genitalia in a prenatal setting. We speculate that the skewed XCI mediates the silence of SRY. In addition, our study emphasizes that combining clinical findings with pedigree analysis is critical for estimating the prognosis of fetuses with sex chromosome abnormalities.

Flow cytometric minimal residual disease measurement accounting for cytogenetics in children with non-high-risk acute lymphoblastic leukemia treated according to the ALL-MB 2008 protocol

BACKGROUND

Quantitative measurement of minimal residual disease (MRD) is the "gold standard" for estimating the response to therapy in childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Nevertheless, the speed of the MRD response differs for different cytogenetic subgroups. Here we present results of MRD measurement in children with BCP-ALL, in terms of genetic subgroups with relation to clinically defined risk groups.

METHODS

A total of 485 children with non-high-risk BCP-ALL with available cytogenetic data and MRD studied at the end-of-induction (EOI) by multicolor flow cytometry (MFC) were included. All patients were treated with standard-risk (SR) of intermediate-risk (ImR) regimens of "ALL-MB 2008" reduced-intensity protocol.

RESULTS AND DISCUSSION

Among all study group patients, 203 were found to have low-risk cytogenetics (ETV6::RUNX1 or high hyperdiploidy), while remaining 282 children were classified in intermediate cytogenetic risk group. For the patients with favorable and intermediate risk cytogenetics, the most significant thresholds for MFC-MRD values were different: 0.03% and 0.04% respectively. Nevertheless, the most meaningful thresholds were different for clinically defined SR and ImR groups. For the SR group, irrespective to presence/absence of favorable genetic lesions, MFC-MRD threshold of 0.1% was the most clinically valuable, although for ImR group the most informative thresholds were different in patients from low-(0.03%) and intermediate (0.01%) cytogenetic risk groups.

CONCLUSION

Our data show that combining clinical risk factors with MFC-MRD measurement is the most useful tool for risk group stratification of children with BCP-ALL in the reduced-intensity protocols. However, this algorithm can be supplemented with cytogenetic data for part of the ImR group.

Cytogenetic Analysis of Satellitome of Madagascar Leaf-Tailed Geckos

Satellite DNA (satDNA) consists of sequences of DNA that form tandem repetitions across the genome, and it is notorious for its diversity and fast evolutionary rate. Despite its importance, satDNA has been only sporadically studied in reptile lineages. Here, we sequenced genomic DNA and PCR-amplified microdissected W chromosomes on the Illumina platform in order to characterize the monomers of satDNA from the Henkel's leaf-tailed gecko U. henkeli and to compare their topology by in situ hybridization in the karyotypes of the closely related Günther's flat-tail gecko U. guentheri and gold dust day gecko P. laticauda. We identified seventeen different satDNAs; twelve of them seem to accumulate in centromeres, telomeres and/or the W chromosome. Notably, centromeric and telomeric regions seem to share similar types of satDNAs, and we found two that seem to accumulate at both edges of all chromosomes in all three species. We speculate that the long-term stability of all-acrocentric karyotypes in geckos might be explained from the presence of specific satDNAs at the centromeric regions that are strong meiotic drivers, a hypothesis that should be further tested.

Cytogenetic Bioindication in Root Meristems for Vitality Assessment of Trees

Our method describes how to collect forest tree root tips in the field, to store them for transfer to the lab, to pretreat root tips in order to arrest cells in metaphase, fix root tips to preserve specific morphological organizations, to stain fixed root tips by Feulgen's Reaction in order to increase contrast, and to prepare the root meristem for analyzing mitotic stages and chromosomal aberrations via light microscopy. We further describe how to classify chromosomal abnormalities and quantify them via aberration indices.

Optical Genome Mapping as a Tool to Unveil New Molecular Findings in Hematological Patients with Complex Chromosomal Rearrangements

Standard cytogenetic techniques (chromosomal banding analysis-CBA, and fluorescence in situ hybridization-FISH) show limits in characterizing complex chromosomal rearrangements and structural variants arising from two or more chromosomal breaks. In this study, we applied optical genome mapping (OGM) to fully characterize two cases of complex chromosomal rearrangements at high resolution. In case 1, an acute myeloid leukemia (AML) patient showing chromothripsis, OGM analysis was fully concordant with classic cytogenetic techniques and helped to better refine chromosomal breakpoints. The OGM results of case 2, a patient with non-Hodgkin lymphoma, were only partially in agreement with previous cytogenetic analyses and helped to better define clonal heterogeneity, overcoming the bias related to clonal selection due to cell culture of cytogenetic techniques. In both cases, OGM analysis led to the identification of molecular markers, helping to define the pathogenesis, classification, and prognosis of the analyzed patients. Despite extensive efforts to study hematologic diseases, standard cytogenetic methods display unsurmountable limits, while OGM is a tool that has the power to overcome these limitations and provide a cytogenetic analysis at higher resolution. As OGM also shows limits in defining regions of a repetitive nature, combining OGM with CBA to obtain a complete cytogenetic characterization would be desirable.

The Discordance between G-Banding Karyotyping and Microarray in Structural Abnormality

BACKGROUND

Cytomolecular genetic laboratory techniques have developed from conventional G-banding karyotyping to whole genome sequencing. Although resolution has greatly increased, various cytogenetic techniques have their advantages and limitations in detecting genomic variations.

METHODS

We compared the chromosomal abnormalities detected by G-banding karyotyping and SNP-based microarray testing in 62 patients from July 2020 to December 2022. We analyzed their difference according to chromosomal abnormalities, including numerical and structural and others.

RESULTS

Of the 62 patients, 28 patients showed chromosomal aberration detected in one or more of the two test methods. Aneuploidy was detected in both methods, while gain and loss less than 3 Mb were only detectable by the microarray. G-banding karyotyping is fundamental to detect structural chromosome rearrangement such as inversions, ring chromosomes, and translocations, but additional breakpoint or unknown origin materials informa-tion obtained from microarray. Loss of heterozygosity was only detectable in microarray, and mosaicism had limitations in both G-banding karyotyping and microarray.

CONCLUSIONS

Various disease cause genomic structural variants, it is very important to detect this. We showed discordance between G-banding karyotyping and SNP based microarray in clinical laboratory. It can be helpful to clinical physicians to decide which diagnostic tool to use.

Comparative Cytogenetic Analysis of Diploid and Triploid Pacific Abalone, Haliotis discus hannai

INTRODUCTION

The Pacific abalone, Haliotis discus hannai, is one of the most commercially important marine shellfish in China. Cell engineering breeding is an important tool in abalone genetic breeding, and the triploids obtained through this method have high commercial value. However, current research mainly focuses on establishing induction methods and evaluating the growth traits of triploids, while there is a lack of basic research on triploid cytogenetics.

METHOD

In this study, Cytogenetic analysis of triploid Haliotis discus hannai larvae (produced by chemical treatment) and diploid larvae was performed.

RESULT

The results showed that triploid H. discus hannai had a chromosome number of 3n = 54, consisting of 30 metacentric (m) and 24 submetacentric (sm) chromosomes, while the diploids had a chromosome number of 2n = 36, consisting of 20 metacentric (m) and 16 submetacentric (sm) chromosomes. Notably, both triploids and diploids displayed variation in the number of NORs and/or their diameter. The average number of NORs in triploid was significantly higher than that in diploids (p < 0.05), but the average diameter of NORs of triploid was no significant different from that of diploid (p > 0.05). Additionally, 5S rDNA localization to 3 submetacentric chromosomes was observed in triploids, compared to 2 submetacentric chromosomes in diploids. The number of 18S rDNA sites displayed positional conservancy and quantitative variability in both diploids and triploids. Specifically, 18S rDNA was found at the end of the chromosome in both groups, with triploids exhibiting a significantly higher number of loci than diploids (p < 0.01).

CONCLUSION

This study provides valuable insights into the cytogenetic characteristics of triploid H. discus hannai, which could facilitate further research on the stability of the chromosome set in this species.

Shallow whole-genome sequencing of bone marrow aspirates in myelodysplastic neoplasms: A retrospective comparison with cytogenetics

Copy number alterations (CNA) are powerful prognostic markers in myelodysplastic neoplasms (MDS) and are routinely analyzed by conventional cytogenetic analysis (CCA) on bone marrow (BM). Although CCA is still the gold standard, it requires extensive hands-on time and highly trained staff for the analysis, making it a laborious technique. To reduce turn-around-time per case, shallow whole genome sequencing (sWGS) technologies offer new perspectives for the diagnostic work-up of this disorder. We compared sWGS with CCA for the detection of CNAs in 33 retrospective BM samples of patients with MDS. Using sWGS, CNAs were detected in all cases and additionally allowed the analysis of three cases for which CCA failed. The prognostic stratification (IPSS-R score) of 27 out of 30 patients was the same with both techniques. In the remaining cases, discrepancies were caused by the presence of balanced translocations escaping sWGS detection in two cases, a subclonal aberration reported with CCA that could not be confirmed by FISH or sWGS, and the presence of an isodicentric chromosome idic(17)(p11) missed by CCA. Since sWGS can almost entirely be automated, our findings indicate that sWGS is valuable in a routine setting validating it as a cost-efficient tool.

Cytogenetics in the management of T-cell acute lymphoblastic leukemia (T-ALL): Guidelines from the Groupe Francophone de Cytogénétique Hématologique (GFCH)

Molecular analysis is the hallmark of T-cell acute lymphoblastic leukemia (T-ALL) categorization. Several T-ALL sub-groups are well recognized based on the aberrant expression of specific transcription factors. This recently resulted in the implementation of eight provisional T-ALL entities into the novel 2022 International Consensus Classification, albeit not into the updated World Health Organization classification system. Despite this extensive molecular characterization, cytogenetic analysis remains the backbone of T-ALL diagnosis in many countries as chromosome banding analysis and fluorescence in situ hybridization are relatively inexpensive techniques to obtain results of diagnostic, prognostic and therapeutic interest. Here, we provide an overview of recurrent chromosomal abnormalities detectable in T-ALL patients and propose guidelines regarding their detection. By referring in parallel to the more general molecular classification approach, we hope to offer a diagnostic framework useful in a broad clinical genetic setting.

Cytogenetics in the management of B-cell acute lymphoblastic leukemia: Guidelines from the Groupe Francophone de Cytogénétique Hématologique (GFCH)

Cytogenetic analysis is mandatory at initial assessment of B-cell acute lymphoblastic leukemia (B-ALL) due to its diagnostic and prognostic value. Results from chromosome banding analysis and complementary FISH are taken into account in therapeutic protocols and further completed by other techniques (RT-PCR, SNP-array, MLPA, NGS, OGM). Indeed, new genomic entities have been identified by NGS, mostly RNA sequencing, such as Ph-like ALL that can benefit from targeted therapy. Here, we have attempted to establish cytogenetic guidelines by reviewing the most recent published data including the novel 5th World Health Organization and International Consensus Classifications. We also focused on newly described cytogenomic entities and indicate alternative diagnostic tools such as NGS technology, as its importance is vastly increasing in the diagnostic setting.

Cytogenetics in the management of mature T-cell and NK-cell neoplasms: Guidelines from the Groupe Francophone de Cytogénétique Hématologique (GFCH)

Mature T-cell and natural killer (NK)-cell neoplasms (MTNKNs) are a highly heterogeneous group of lymphomas that represent 10-15 % of lymphoid neoplasms and have usually an aggressive behavior. Diagnosis can be challenging due to their overlapping clinical, histological and immunophenotypic features. Genetic data are not a routine component of the diagnostic algorithm for most MTNKNs. Indeed, unlike B-cell lymphomas, the genomic landscape of MTNKNs is not fully understood. Only few characteristic rearrangements can be easily identified with conventional cytogenetic methods and are an integral part of the diagnostic criteria, for instance the t(14;14)/inv(14) or t(X;14) abnormality harbored by 95 % of patients with T-cell prolymphocytic leukemia, or the ALK gene translocation observed in some forms of anaplastic large cell lymphoma. However, advances in molecular and cytogenetic techniques have brought new insights into MTNKN pathogenesis. Several recurrent genetic alterations have been identified, such as chromosomal losses involving tumor suppressor genes (SETD2, CDKN2A, TP53) and gains involving oncogenes (MYC), activating mutations in signaling pathways (JAK-STAT, RAS), and epigenetic dysregulation, that have improved our understanding of these pathologies. This work provides an overview of the cytogenetics knowledge in MTNKNs in the context of the new World Health Organization classification and the International Consensus Classification of hematolymphoid tumors. It describes key genetic alterations and their clinical implications. It also proposes recommendations on cytogenetic methods for MTNKN diagnosis.

Retrospective Evaluation of Cytogenetic Effects Induced by Internal Radioiodine Exposure: A 27-Year Follow-Up Study

Radioiodine (131I) is widely used in the treatment of hyperthyroidism and as an effective ablative therapy for differentiated thyroid cancer. Radioiodine (131I) constitutes 90% of the currently used therapies in the field of nuclear medicine. Here, we report the cytogenetic findings of a long-term follow-up study of 27 years on a male patient who received two rounds of radioiodine treatment within a span of 26 months between 1992 and 1994 for his papillary thyroid cancer. A comprehensive cytogenetic follow-up study utilizing cytokinesis blocked micronucleus assay, dicentric chromosome assay, genome wide translocations and inversions was initiated on this patient since the first administration of radioiodine in 1992. Frequencies of micronuclei (0.006/cell) and dicentric chromosomes (0.008/cell) detected in the current study were grossly similar to that reported earlier in 2019. The mFISH analysis detected chromosome aberrations in 8.6% of the cells in the form of both unbalanced and balanced translocations. Additionally, a clonal translocation involving chromosomes 14p; 15q was observed in 2 of the 500 cells analyzed. Out of the 500 cells examined, one cell showed a complex translocation (involving chromosomes 9, 10, and 16) besides 5 other chromosome rearrangements. Collectively, our study indicates that the past radioiodine exposure results in long-lasting chromosome damage and that the persistence of translocations can be useful for both retrospective biodosimetry and for monitoring chromosome instability in the lymphocytes of radioiodine exposed individuals.

Clinical Validation and Diagnostic Utility of Optical Genome Mapping in Prenatal Diagnostic Testing

The standard-of-care diagnostic prenatal testing includes a combination of cytogenetic methods, such as karyotyping, fluorescence in situ hybridization (FISH), and chromosomal microarray (CMA), using either direct or cultured amniocytes or chorionic villi sampling. However, each technology has its limitations: karyotyping has a low resolution (>5 Mb), FISH is targeted, and CMA does not detect balanced structural variations (SVs). These limitations necessitate the use of multiple tests, either simultaneously or sequentially, to reach a genetic diagnosis. Optical genome mapping (OGM) is an emerging technology that can detect several classes of SVs in a single assay, but it has not been evaluated in the prenatal setting. This validation study analyzed 114 samples that were received in our laboratory for traditional cytogenetic analysis with karyotyping, FISH, and/or CMA. OGM was 100% concordant in identifying the 101 aberrations that included 29 interstitial/terminal deletions, 28 duplications, 26 aneuploidies, 6 absence of heterozygosity regions, 3 triploid genomes, 4 isochromosomes, and 1 translocation; and the method revealed the identity of 3 marker chromosomes and 1 chromosome with additional material not determined by karyotyping. In addition, OGM detected 64 additional clinically reportable SVs in 43 samples. OGM has a standardized laboratory workflow and reporting solution that can be adopted in routine clinical laboratories and demonstrates the potential to replace the current standard-of-care methods for prenatal diagnostic testing.

Cytogenetics in Oral Cancer: A Comprehensive Update

AIM

To evaluate the application of cytogenetic techniques in determining the diagnosis, prognosis, and therapeutics in oral cancer.

BACKGROUND

Genetic aberrations that play an important role in oral oncogenesis demand substantial research for in-depth characterization of the tumor. Cytogenetic techniques have the potential to detect these aberrations. This review highlights about various cytogenetic approaches in cancer and how these findings support its application in the field of oral oncology.

METHODS

Google scholar search was done for articles on cancer cytogenetics, and in particular, PubMed database was queried for articles published from 2015 to 2020 using keywords cytogenetics, chromosomal aberrations, conventional cytogenetics, karyotyping, banding techniques, molecular cytogenetics, fluorescent in situ hybridization, spectral karyotyping, comparative genomic hybridization, multiplex ligation probe analysis, and next-generation sequencing (NGS) in oral cancer. Abstracts were reviewed, and relevant full text was accessed to extract the cytogenetic findings in oral cancer.

RESULTS

Data regarding various cytogenetic approaches from conventional to molecular techniques have been published in oral cancer. They convey a highly complex cytogenetic finding from gross chromosomal aberrations to specific gene mutations in oral cancer.

CONCLUSION

Crucial information in the development and progression of oral cancer is achieved through cytogenetic findings in particular with the molecular cytogenetic techniques. Novel technologies like NGS have emerged in recent years that hold promise in the detection of these alterations more efficiently.

CLINICAL SIGNIFICANCE

An appraisal of cytogenetic analysis in oral cancer helps to determine the diagnosis and the most important prognosticators. It assists in building targeted therapies for patient benefit.

Lizards as Model Organisms of Sex Chromosome Evolution: What We Really Know from a Systematic Distribution of Available Data?

Lizards represent unique model organisms in the study of sex determination and sex chromosome evolution. Among tetrapods, they are characterized by an unparalleled diversity of sex determination systems, including temperature-dependent sex determination (TSD) and genetic sex determination (GSD) under either male or female heterogamety. Sex chromosome systems are also extremely variable in lizards. They include simple (XY and ZW) and multiple (X1X2Y and Z1Z2W) sex chromosome systems and encompass all the different hypothesized stages of diversification of heterogametic chromosomes, from homomorphic to heteromorphic and completely heterochromatic sex chromosomes. The co-occurrence of TSD, GSD and different sex chromosome systems also characterizes different lizard taxa, which represent ideal models to study the emergence and the evolutionary drivers of sex reversal and sex chromosome turnover. In this review, we present a synthesis of general genome and karyotype features of non-snakes squamates and discuss the main theories and evidences on the evolution and diversification of their different sex determination and sex chromosome systems. We here provide a systematic assessment of the available data on lizard sex chromosome systems and an overview of the main cytogenetic and molecular methods used for their identification, using a qualitative and quantitative approach.

Cytogenetically Elusive Sex Chromosomes in Scincoidean Lizards

The lizards of the species-rich clade Scincoidea including cordylids, gerrhosaurids, skinks, and xantusiids, show an almost cosmopolitan geographical distribution and a remarkable ecological and morphological divergence. However, previous studies revealed limited variability in cytogenetic traits. The sex determination mode was revealed only in a handful of gerrhosaurid, skink, and xantusiid species, which demonstrated either ZZ/ZW or XX/XY sex chromosomes. In this study, we explored the karyotypes of six species of skinks, two species of cordylids, and one gerrhosaurid. We applied conventional and molecular cytogenetic methods, including C-banding, fluorescence in situ hybridization with probes specific for telomeric motifs and rDNA loci, and comparative genomic hybridization. The diploid chromosome numbers are rather conserved among these species, but the chromosome morphology, the presence of interstitial telomeric sequences, and the topology of rDNA loci vary significantly. Notably, XX/XY sex chromosomes were identified only in Tiliqua scincoides, where, in contrast to the X chromosome, the Y chromosome lacks accumulations of rDNA loci. We confirm that within the lizards of the scincoidean clade, sex chromosomes remained in a generally poor stage of differentiation.

Targeted long-read sequencing identifies missing disease-causing variation

Despite widespread clinical genetic testing, many individuals with suspected genetic conditions lack a precise diagnosis, limiting their opportunity to take advantage of state-of-the-art treatments. In some cases, testing reveals difficult-to-evaluate structural differences, candidate variants that do not fully explain the phenotype, single pathogenic variants in recessive disorders, or no variants in genes of interest. Thus, there is a need for better tools to identify a precise genetic diagnosis in individuals when conventional testing approaches have been exhausted. We performed targeted long-read sequencing (T-LRS) using adaptive sampling on the Oxford Nanopore platform on 40 individuals, 10 of whom lacked a complete molecular diagnosis. We computationally targeted up to 151 Mbp of sequence per individual and searched for pathogenic substitutions, structural variants, and methylation differences using a single data source. We detected all genomic aberrations-including single-nucleotide variants, copy number changes, repeat expansions, and methylation differences-identified by prior clinical testing. In 8/8 individuals with complex structural rearrangements, T-LRS enabled more precise resolution of the mutation, leading to changes in clinical management in one case. In ten individuals with suspected Mendelian conditions lacking a precise genetic diagnosis, T-LRS identified pathogenic or likely pathogenic variants in six and variants of uncertain significance in two others. T-LRS accurately identifies pathogenic structural variants, resolves complex rearrangements, and identifies Mendelian variants not detected by other technologies. T-LRS represents an efficient and cost-effective strategy to evaluate high-priority genes and regions or complex clinical testing results.

Optical genome mapping enables constitutional chromosomal aberration detection

Chromosomal aberrations including structural variations (SVs) are a major cause of human genetic diseases. Their detection in clinical routine still relies on standard cytogenetics. Drawbacks of these tests are a very low resolution (karyotyping) and the inability to detect balanced SVs or indicate the genomic localization and orientation of duplicated segments or insertions (copy number variant [CNV] microarrays). Here, we investigated the ability of optical genome mapping (OGM) to detect known constitutional chromosomal aberrations. Ultra-high-molecular-weight DNA was isolated from 85 blood or cultured cells and processed via OGM. A de novo genome assembly was performed followed by structural variant and CNV calling and annotation, and results were compared to known aberrations from standard-of-care tests (karyotype, FISH, and/or CNV microarray). In total, we analyzed 99 chromosomal aberrations, including seven aneuploidies, 19 deletions, 20 duplications, 34 translocations, six inversions, two insertions, six isochromosomes, one ring chromosome, and four complex rearrangements. Several of these variants encompass complex regions of the human genome involved in repeat-mediated microdeletion/microduplication syndromes. High-resolution OGM reached 100% concordance compared to standard assays for all aberrations with non-centromeric breakpoints. This proof-of-principle study demonstrates the ability of OGM to detect nearly all types of chromosomal aberrations. We also suggest suited filtering strategies to prioritize clinically relevant aberrations and discuss future improvements. These results highlight the potential for OGM to provide a cost-effective and easy-to-use alternative that would allow comprehensive detection of chromosomal aberrations and structural variants, which could give rise to an era of "next-generation cytogenetics."

Next-generation cytogenetics: Comprehensive assessment of 52 hematological malignancy genomes by optical genome mapping

Somatic structural variants (SVs) are important drivers of cancer development and progression. In a diagnostic set-up, especially for hematological malignancies, the comprehensive analysis of all SVs in a given sample still requires a combination of cytogenetic techniques, including karyotyping, FISH, and CNV microarrays. We hypothesize that the combination of these classical approaches could be replaced by optical genome mapping (OGM). Samples from 52 individuals with a clinical diagnosis of a hematological malignancy, divided into simple (<5 aberrations, n = 36) and complex (≥5 aberrations, n = 16) cases, were processed for OGM, reaching on average: 283-fold genome coverage. OGM called a total of 918 high-confidence SVs per sample, of which, on average, 13 were rare and >100 kb. In addition, on average, 73 CNVs were called per sample, of which six were >5 Mb. For the 36 simple cases, all clinically reported aberrations were detected, including deletions, insertions, inversions, aneuploidies, and translocations. For the 16 complex cases, results were largely concordant between standard-of-care and OGM, but OGM often revealed higher complexity than previously recognized. Detailed technical comparison with standard-of-care tests showed high analytical validity of OGM, resulting in a sensitivity of 100% and a positive predictive value of >80%. Importantly, OGM resulted in a more complete assessment than any previous single test and most likely reported the most accurate underlying genomic architecture (e.g., for complex translocations, chromoanagenesis, and marker chromosomes). In conclusion, the excellent concordance of OGM with diagnostic standard assays demonstrates its potential to replace classical cytogenetic tests as well as to rapidly map novel leukemia drivers.

Large-scale comparative analysis of cytogenetic markers across Lepidoptera

Fluorescence in situ hybridization (FISH) allows identification of particular chromosomes and their rearrangements. Using FISH with signal enhancement via antibody amplification and enzymatically catalysed reporter deposition, we evaluated applicability of universal cytogenetic markers, namely 18S and 5S rDNA genes, U1 and U2 snRNA genes, and histone H3 genes, in the study of the karyotype evolution in moths and butterflies. Major rDNA underwent rather erratic evolution, which does not always reflect chromosomal changes. In contrast, the hybridization pattern of histone H3 genes was well conserved, reflecting the stable organisation of lepidopteran genomes. Unlike 5S rDNA and U1 and U2 snRNA genes which we failed to detect, except for 5S rDNA in a few representatives of early diverging lepidopteran lineages. To explain the negative FISH results, we used quantitative PCR and Southern hybridization to estimate the copy number and organization of the studied genes in selected species. The results suggested that their detection was hampered by long spacers between the genes and/or their scattered distribution. Our results question homology of 5S rDNA and U1 and U2 snRNA loci in comparative studies. We recommend the use of histone H3 in studies of karyotype evolution.

Cytogenetic monitoring of peripheral blood lymphocytes from medical radiation professionals occupationally exposed to low-dose ionizing radiation

In order to assess the health risk of low-dose radiation to radiation professionals, monitoring is performed through chromosomal aberration analysis and micronuclei (MN) analysis. MN formation has drawbacks for monitoring in the low-dose range. Nucleoplasmic bridge (NPB) analysis, with a lower background level, has good dose-response relationships at both high and relatively low dose ranges. Dicentric and ring chromosomes were analyzed in 199 medical radiation professionals, and NPB/MN yields were analyzed in 205 radiation professionals. The effects of sex, age of donor, types of work, and length of service on these cytogenetic endpoints were also analyzed. The yields of the three cytogenetic endpoints were significantly higher in radiation professionals versus controls. Frequencies of dicentric plus ring chromosomes were affected by length of service. NPB frequencies were influenced by type of work and length of service. MN yields were affected not only by types of work and length of service but also by donor sex and age. In conclusion, dicentric plus ring chromosomes, NPB, and MN can be induced by low-dose radiation in radiation professionals. NPB is a potential biomarker to assess the health risk of occupational low-dose radiation exposure.

Multiplex ligation-dependent probe amplification and fluorescence in situ hybridization for detecting chromosome abnormalities in myelodysplastic syndromes: A retrospective study

This study aimed to compare interphase fluorescence in situ hybridization (iFISH) and multiplex ligation dependent probe amplification (MLPA) for identifying genetic changes in myelodysplastic syndromes (MDS).The frequencies of cytogenetic changes in MDS patients treated at the Institute of Hematology and Blood Disease Hospital (China) in 2009 to 2018 were assessed by iFISH based on bone marrow samples. Then, the effectiveness of MLPA in detecting these anomalies was evaluated.Specimens from 287 MDS patients were assessed. A total of 36.9% (103/279) of MDS cases had chromosomal abnormalities detected by iFISH; meanwhile, 44.1% (123/279) harbored ≥1 copy-number variation (CNV) based on MLPA: +8 (n=46), -5 (n = 39), -7 (n = 27), del 20 (n = 32) and del 17 (n = 17). Overall, 0 to 4 aberrations/case were detected by MLPA, suggesting the heterogeneous and complex nature of MDS cytogenetics. There were 29 cases detected by MLPA, which were undetected by FISH or showed low signals. Sixteen of these cases had their risk classification changed due to MLPA detection, including 9 reassigned to the high-risk IPSS-R group. These findings demonstrated that MLPA is highly efficient in assessing cytogenetic anomalies, with data remarkably corroborating FISH findings (overall consistency of 97.1%). The sensitivities of MLPA in detecting +8, -5, -7, del 20 and del 17 were 92.3%, 97.1%, 100%, 100%, and 90%, respectively, with specificities of 95.8%, 97.6%, 97.7%, 97.6%, and 97%, respectively.MLPA represents a reliable approach, with greater efficiency, accuracy, and speed than iFISH in identifying cytogenetic aberrations in MDS.

Analysis of the possible cytogenetic mechanism for overcoming hybrid lethality in an interspecific cross between Nicotiana suaveolens and Nicotiana tabacum

Hybrid lethality is a type of reproductive isolation in which hybrids die before maturation, due to the interaction between the two causative genes derived from each of the hybrid parents. The interspecific hybrid of Nicotiana suaveolens × Nicotiana tabacum is a model plant used in studies on hybrid lethality. While most of the progeny produced from such a cross die, some individuals grow normally and mature. Separately, a technique for producing mature hybrids by artificial culture has been developed. However, the mechanism by which hybrids overcome lethality, either spontaneously or by artificial culture, remains unclear. In the present study, we found that some hybrids that overcome lethality, either spontaneously or by artificial culture, lack the distal part of the Q chromosome, a region that includes the gene responsible for lethality. Quantitative polymerase chain reaction results suggested that the distal deletion of the Q chromosome, detected in some hybrid seedlings that overcome lethality, is caused by reciprocal translocations between homoeologous chromosomes. The results showed that chromosomal instability during meiosis in amphidiploid N. tabacum as well as during artificial culturing of hybrid seedlings is involved in overcoming hybrid lethality in interspecific crosses of the genus Nicotiana.

Chromosomes in the genomic age. Preserving cytogenomic competence of diagnostic genome laboratories

Participation of clinical genetic laboratories in External Quality Assessment schemes (EQAs) is a powerful method to ascertain if any improvement or additional training is required in the diagnostic service. Here, we provide evidence from recent EQAs that the competence in recognizing and interpreting cytogenetic aberrations is variable and could impact patient management. We identify several trends that could affect cytogenomic competence. Firstly, as a result of the age distribution among clinical laboratory geneticists (CLGs) registered at the European Board of Medical Genetics, about 25-30% of those with experience in cytogenetics will retire during the next decade. At the same time, there are about twice as many molecular geneticists to cytogeneticists among the younger CLGs. Secondly, when surveying training programs for CLG, we observed that not all programs guarantee that candidates gather sufficient experience in clinical cytogenomics. Thirdly, we acknowledge that whole genome sequencing (WGS) has a great attraction to biomedical scientists that wish to enter a training program for CLG. This, with a larger number of positions available, makes a choice for specialization in molecular genetics logical. However, current WGS technology cannot provide a diagnosis in all cases. Understanding the etiology of chromosomal rearrangements is essential for appropriate follow-up and for ascertaining recurrence risks. We define the minimal knowledge a CLG should have about cytogenomics in a world dominated by WGS, and discuss how laboratory directors and boards of professional organizations in clinical genetics can uphold cytogenomic competence by providing adequate CLG training programs and attracting sufficient numbers of trainees.

Bridging the Gap between Vertebrate Cytogenetics and Genomics with Single-Chromosome Sequencing (ChromSeq)

The study of vertebrate genome evolution is currently facing a revolution, brought about by next generation sequencing technologies that allow researchers to produce nearly complete and error-free genome assemblies. Novel approaches however do not always provide a direct link with information on vertebrate genome evolution gained from cytogenetic approaches. It is useful to preserve and link cytogenetic data with novel genomic discoveries. Sequencing of DNA from single isolated chromosomes (ChromSeq) is an elegant approach to determine the chromosome content and assign genome assemblies to chromosomes, thus bridging the gap between cytogenetics and genomics. The aim of this paper is to describe how ChromSeq can support the study of vertebrate genome evolution and how it can help link cytogenetic and genomic data. We show key examples of ChromSeq application in the refinement of vertebrate genome assemblies and in the study of vertebrate chromosome and karyotype evolution. We also provide a general overview of the approach and a concrete example of genome refinement using this method in the species Anolis carolinensis.

Cytogenetic and Fluorescence in situ Hybridization Profile of Pediatric Acute Lymphoblastic Leukemia in a University Hospital in South India

OBJECTIVE

The purpose of this study was to evaluate the cytogenetic and fluorescent in situ hybridization (FISH) profile in children with acute lymphoblastic leukemia (ALL), referred to a university hospital in a 5-year 6-month period.

SUBJECTS AND METHODS

Cytogenetic analysis of the bone marrow aspirate specimens of 91 patients was performed by standard Giemsa (G)-banding and interphase FISH (iFISH).

RESULTS

The frequency of chromosomal abnormalities detected by G-banding was 29.5%, and the frequency of nonrandom abnormalities with independent prognostic significance identified by iFISH was 46.4%. The abnormality with the highest frequency was gain of RUNX1 (n = 18, 21.4%), followed by ETV6/RUNX1 fusion (n = 7, 8.3%), and gain of KMT2A (n = 6, 7.1%). Additionally, rarely reported gains of ETV6, PBX1, and ABL1 were observed at a frequency of 6% (n = 5), and the deletion of ETV6 and TCF3 was seen at a frequency of 3.6% (n = 3) and 2.3% (n = 2), respectively. A 10-year old with intrachromosomal amplification of chromosome 21 was also observed.

CONCLUSIONS

This study strengthens and widens the current knowledge of the cytogenetic landscape of pediatric ALL.

Modified Culture System and Combination of FICTION Could Increase the Detection Rate of Abnormalities in Multiple Myeloma

OBJECTIVE

Conventional karyotyping of multiple myeloma (MM) is hampered by the low mitotic index of plasma cells (PCs), and low proportion of PCs in some specimens may lead to false negative results in fluorescence in situ hybridisation (FISH) detection.

METHODS

Bone marrow cells were cultured in an ordinary medium for 24 h or in a medium containing 10 ng/mL IL-6 and 40 ng/mL GM-CSF for 6 d. Fluorescence immunophenotyping and interphase cytogenetics as a tool for the investigation of neoplasms (FICTION) was also conducted, combining CD138 fluorescent immunophenotype and FISH.

RESULTS

Under modified culture conditions, the successful rate of culture and abnormality detection rate during karyotype analysis increased to 86.4% and 40.9%, respectively. The abnormality detection rate of FICTION (89.5%) was significantly higher than that of FISH (60.0%). The genetic abnormality detection rate increased to 92.3% when FICTION and karyotyping were conducted under modified culture conditions.

CONCLUSION

The established modified culture system could improve karyotyping quality in MM. Due to its obvious advantages compared with FISH, FICTION is recommended for detecting genetic abnormalities in MM.

Molecular Cytogenetics (Fluorescence In Situ Hybridization - FISH and Fluorochrome Banding): Resolving Species Relationships and Genome Organization

Fluorochrome banding (chromomycin, Hoechst, and DAPI) and fluorescence in situ hybridization (FISH) are excellent molecular cytogenetic tools providing various possibilities in the study of chromosomal evolution and genome organization. The constitutive heterochromatin and rRNA genes are the most widely used FISH markers. The rDNA is organized into two distinct gene families (18S-5.8S-26S and 5S) whose number and location vary within the complex of closely related species. Therefore, they are widely used as chromosomal landmarks to provide valuable evidence concerning genome evolution at chromosomal levels.

Targeted Analysis of Chromatin Events (TACE)

Visualization of meiotic chromatin from pollen mother cells has become an essential technique to study meiosis in the model plant Arabidopsis thaliana. Here we present an advanced cytogenetic method that combines improved immunocytology with chromosome painting, thereby generating a tool to quantitatively analyze localization of proteins to any given genomic region. Proteins involved in different processes such as DNA double-strand break formation and recombinational repair can be visualized on meiotic chromatin with the additional feature of assessing their abundance at specific chromosomal locations.

Telomere aberrations, including telomere loss, doublets, and extreme shortening, are increased in patients with infertility

OBJECTIVE

To test the hypothesis that telomere shortening and/or loss are risk factors for infertility.

DESIGN

Retrospective analysis of the telomere status in patients with infertility using conventional cytogenetic data collected prospectively.

SETTING

Academic centers.

PATIENT(S)

Cytogenetic slides with cultured peripheral lymphocytes from 50 patients undergoing fertility treatment and 150 healthy donors, including 100 donors matched for age.

INTERVENTION(S)

Cytogenetic slides were used to detect chromosomal and telomere aberrations.

MAIN OUTCOME MEASURE(S)

Telomere length and telomere aberrations were analyzed after telomere and centromere staining.

RESULT(S)

The mean telomere length of patients consulting for infertility was significantly less than that of healthy donors of similar age. Moreover, patients with infertility showed significantly more extreme telomere loss and telomere doublet formation than healthy controls. Telomere shortening and/or telomere aberrations were more pronounced in patients with structural chromosomal aberrations. Dicentric chromosomes were identified in 6/13 patients, with constitutional chromosomal aberrations leading to chromosomal instability that correlated with chromosomal end-to-end fusions.

CONCLUSION(S)

Our findings demonstrate the feasibility of analyzing telomere aberrations in addition to chromosomal aberrations, using cytogenetic slides. Telomere attrition and/or dysfunction represent the main common cytogenetic characteristic of patients with infertility, leading to potential implications for fertility assessment. Pending further studies, these techniques that correlate the outcome of assisted reproduction and telomere integrity status may represent a novel and useful diagnostic and/or prognostic tool for medical care in this field.

Clinical implications of conventional cytogenetics, fluorescence in situ hybridization (FISH) and molecular testing in chronic myeloid leukaemia patients in the tyrosine kinase inhibitor era - A review

Chronic myeloid leukaemia (CML) provides an illustrative disease model for both molecular pathogenesis of cancer and rational drug therapy. Imatinib mesylate (IM), a BCR-ABL1 targeted tyrosine kinase inhibitor (TKI) drug, is the first line gold standard drug for CML treatment. Conventional cytogenetic analysis (CCA) can identify the standard and variant Philadelphia (Ph) chromosome, and any additional complex chromosome abnormalities at diagnosis as well as during treatment course. Fluorescence in situ hybridization (FISH) is especially important for cells of CML patients with inadequate or inferior quality metaphases or those with variant Ph translocations. CCA in conjunction with FISH can serve as powerful tools in all phases of CML including the diagnosis, prognosis, risk stratification and monitoring of cytogenetic responses to treatment. Molecular techniques such as reverse transcriptase-polymerase chain reaction (RT-PCR) is used for the detection of BCR-ABL1 transcripts at diagnosis whereas quantitative reverse transcriptase-polymerase chain reaction (qRTPCR) is used at the time of diagnosis as well as during TKI therapy for the quantitation of BCR-ABL1 transcripts to evaluate the molecular response and minimal residual disease (MRD). Despite the excellent treatment results obtained after the introduction of TKI drugs, especially Imatinib mesylate (IM), resistance to TKIs develops in approximately 35% - 40% of CML patients on TKI therapy. Since point mutations in BCR-ABL1 are a common cause of IM resistance, mutation analysis is important in IM resistant patients. Mutations are reliably detected by nested PCR amplification of the translocated ABL1 kinase domain followed by direct sequencing of the entire amplified kinase domain. The objective of this review is to highlight the importance of regular and timely CCA, FISH analysis and molecular testing in the diagnosis, prognosis, assessment of therapeutic efficacy, evaluation of MRD and in the detection of BCR-ABL1 kinase mutations which cause therapeutic resistance in adult CML patients.

Chromosome Mapping of 5S Ribosomal Genes in Indo-Pacific and Atlantic Muraenidae: Comparative Analysis by Dual Colour Fluorescence In Situ Hybridisation

The Muraenidae is one of the largest and most complex anguilliform families. Despite their abundance and important ecological roles, morays are little studied, especially cytogenetically, and both their phylogenetic relationships and the taxonomy of their genera are controversial. With the aim of extending the karyology of this fish group, the chromosomal mapping of the 5S ribosomal gene family was performed on seven species belonging to the genera Muraena and Gymnothorax from both the Atlantic and Pacific oceans. Fluorescence in situ hybridisation (FISH) experiments were realized using species-specific 5S rDNA probes; in addition, two-colour FISH was performed to investigate the possible association with the 45S ribosomal gene family. Multiple 5S rDNA clusters, located either in species-specific or in possibly homoeologous chromosomes, were found. Either a syntenic or different chromosomal location of the two ribosomal genes was detected. Our results revealed variability in the number and location of 5S rDNA clusters and confirmed a substantial conservation of the number and location of the 45S rDNA.

State-wide utilization and performance of traditional and cell-free DNA-based prenatal testing pathways: the Victorian Perinatal Record Linkage (PeRL) study

OBJECTIVES

To perform individual record linkage of women undergoing screening with cell-free DNA (cfDNA), combined first-trimester screening (CFTS), second-trimester serum screening (STSS), and/or prenatal and postnatal cytogenetic testing with the aim to (1) obtain population-based estimates of utilization of prenatal screening and invasive diagnosis, (2) analyze the performance of different prenatal screening strategies, and (3) report the residual risk of any major chromosomal abnormality following a low-risk aneuploidy screening result.

METHODS

This was a retrospective study of women residing in the state of Victoria, Australia, who underwent prenatal screening or invasive prenatal diagnosis in 2015. Patient-funded cfDNA referrals from multiple providers were merged with state-wide results for government-subsidized CFTS, STSS and invasive diagnostic procedures. Postnatal cytogenetic results from products of conception and infants up to 12 months of age were obtained to ascertain cases of false-negative screening results and atypical chromosomal abnormalities. Individual record linkage was performed using LinkageWiz^TM .

RESULTS

During the study period, there were 79 140 births and 66 166 (83.6%) women underwent at least one form of aneuploidy screening. Linkage data were complete for 93.5% (n = 61 877) of women who underwent screening, and of these, 73.2% (n = 45 275) had CFTS alone, 20.2% (n = 12 486) had cfDNA alone; 5.3% (n = 3268) had STSS alone, 1.3% (n = 813) had both CFTS and cfDNA, and < 0.1% (n = 35) had both STSS and cfDNA. CFTS had a combined sensitivity for trisomies 21 (T21), 18 (T18) and 13 (T13) of 89.57% (95% CI, 82.64-93.93%) for a screen-positive rate (SPR) of 2.94%. There were 12 false-negative results in the CFTS pathway, comprising 10 cases of T21, one of T18 and one of T13. cfDNA had a combined sensitivity for T21, T18 and T13 of 100% (95% CI, 95.00-100%) for a SPR of 1.21%. When high-risk cfDNA results for any chromosome (including the sex chromosomes) and failed cfDNA tests were treated as screen positives, the SPR for cfDNA increased to 2.42%. The risk of any major chromosomal abnormality (including atypical abnormalities) detected on prenatal or postnatal diagnostic testing after a low-risk screening result was 1 in 1188 for CFTS (n = 37) and 1 in 762 for cfDNA (n = 16) (P = 0.13). The range of chromosomal abnormalities detected after a low-risk cfDNA result included pathogenic copy-number variants (n = 6), triploidy (n = 3), rare autosomal trisomies (n = 3) and monosomy X (n = 2).

CONCLUSIONS

Our state-wide record-linkage analysis delineated the utilization and clinical performance of the multitude of prenatal screening pathways available to pregnant women. The sensitivity of cfDNA for T21, T18 and T13 was clearly superior to that of CFTS. While there was no statistically significant difference in the residual risk of any major chromosomal abnormality after a low-risk CFTS or cfDNA result, there were fewer live infants diagnosed with a major chromosomal abnormality in the cfDNA cohort. These data provide valuable population-based evidence to inform practice recommendations and health policies. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

The investigation of the in vivo cytogenetic effects of psychotropic drugs in human lymphocyte cultures

The connection of nearly all current antipsychotic drugs to their in vivo cytogenetic activity has not been yet fully investigated. Fluvoxamine, Valproic acid (VA) and Haloperidol (HLP) are three universally common consumed psychotic drugs whereas used to treat several psychiatric disorders. This study aims to investigate the cytogenetic effects of these three psychotropic drugs by evaluating the frequency of Sister Chromatid Exchanges (SCEs) and the Proliferation Rate Index (PRI) in cultured lymphocytes. Fifteen patients with psychiatric disorders (i.e. depression, bipolar and schizophrenia) consisting of smokers and non-smokers were included. Estimation of SCEs was used as a sensitive biomarker of the potential cytotoxicity, while PRI was used as a valuable marker of cytostatic activity. A significant increase of SCEs in the cultured lymphocyte of the smoker controls (P= 0.013) was found in compared to the non-smoker controls. This study found that there is no difference in the average of SCEs values in lymphocytes isolated from the smoker and non-smoker patients treated with Fluvoxamine, Valproic acid and Haloperidol (P&gt; 0.05). A significant difference of PRI (P= 0.036) in the lymphocytes of smoker controls compared to those of the non-smoker controls were detected. This study also found a significant difference with respect to PRI between the three patient groups (P= 0.017). These results illustrated that treatment (monotherapy) of psychiatric patients with Fluvoxamine, Valproic acid, and Haloperidol exerts a significant cytostatic but not cytotoxic effect on their lymphocytes whereas these effects are intensified by smoking.

Molecular Cytogenomic Characterization of the Murine Breast Cancer Cell Lines C-127I, EMT6/P and TA3 Hauschka

BACKGROUND

To test and introduce effective and less toxic breast cancer (BC) treatment strategies, animal models, including murine BC cell lines, are considered as perfect platforms. Strikingly, the knowledge on the genetic background of applied BC cell lines is often sparse though urgently necessary for their targeted and really justified application.

METHODS

In this study, we performed the first molecular cytogenetic characterization for three murine BC cell lines C-127I, EMT6/P and TA3 Hauschka. Besides fluorescence in situ hybridization-banding, array comparative genomic hybridization was also applied. Thus, overall, an in silico translation for the detected imbalances and chromosomal break events in the murine cell lines to the corresponding homologous imbalances in humans could be provided. The latter enabled a comparison of the murine cell line with human BC cytogenomics.

RESULTS

All three BC cell lines showed a rearranged karyotype at different stages of complexity, which can be interpreted carefully as reflectance of more or less advanced tumor stages.

CONCLUSIONS

Accordingly, the C-127I cell line would represent the late stage BC while the cell lines EMT6/P and TA3 Hauschka would be models for the premalignant or early BC stage and an early or benign BC, respectively. With this cytogenomic information provided, these cell lines now can be applied really adequately in future research studies.

A randomised phase II trial of hydroxychloroquine and imatinib versus imatinib alone for patients with chronic myeloid leukaemia in major cytogenetic response with residual disease

In chronic-phase chronic myeloid leukaemia (CP-CML), residual BCR-ABL1+ leukaemia stem cells are responsible for disease persistence despite TKI. Based on in vitro data, CHOICES (CHlorOquine and Imatinib Combination to Eliminate Stem cells) was an international, randomised phase II trial designed to study the safety and efficacy of imatinib (IM) and hydroxychloroquine (HCQ) compared with IM alone in CP-CML patients in major cytogenetic remission with residual disease detectable by qPCR. Sixty-two patients were randomly assigned to either arm. Treatment 'successes' was the primary end point, defined as ≥0.5 log reduction in 12-month qPCR level from trial entry. Selected secondary study end points were 24-month treatment 'successes', molecular response and progression at 12 and 24 months, comparison of IM levels, and achievement of blood HCQ levels >2000 ng/ml. At 12 months, there was no difference in 'success' rate (p = 0.58); MMR was achieved in 80% (IM) vs 92% (IM/HCQ) (p = 0.21). At 24 months, the 'success' rate was 20.8% higher with IM/HCQ (p = 0.059). No patients progressed. Seventeen serious adverse events, including four serious adverse reactions, were reported; diarrhoea occurred more frequently with combination. IM/HCQ is tolerable in CP-CML, with modest improvement in qPCR levels at 12 and 24 months, suggesting autophagy inhibition maybe of clinical value in CP-CML.

A Small-Molecule AIE Chromosome Periphery Probe for Cytogenetic Studies

The chromosome periphery (CP) is a complex network that covers the outer surface of chromosomes. It acts as a carrier of nucleolar components, helps maintain chromosome structure, and plays an important role in mitosis. Current methods for fluorescence imaging of CP largely rely on immunostaining. We herein report a small-molecule fluorescent probe, ID-IQ, which possesses aggregation-induced emission (AIE) property, for CP imaging. By labelling the CP, ID-IQ sharply highlighted the chromosome boundaries, which enabled rapid segmentation of touching and overlapping chromosomes, direct identification of the centromere, and clear visualization of chromosome morphology. ID-IQ staining was also compatible with fluorescence in situ hybridization and could assist the precise location of the gene in designated chromosome. Altogether, this study provides a versatile cytogenetic tool for improved chromosome analysis, which greatly benefits the clinical diagnostic testing and genomic research.

Myelodysplastic Syndrome with t(1;14),t(1;17),t(1;19) Transforms to AML-M5: A Case Report and Literature Review

Chromosomal aberrations play an important role in the incidence of myelodysplastic syndromes (MDS) and development to acute myeloid leukemia (AML). We report a case of a 62-year-old male patient diagnosed with MDS with excess blasts. The karyotype was 45, XY,+1,+1,-7,-10,-22,t(1;14) (q21;q32),t(1;17)(q21;p13),t(1;19)(q21;p13). The patient and his family refused treatment for financial reasons. After 2 months, the patient's MDS transformed into acute myeloid monocytic leukemia (AML-M5). This case of MDS with poor prognosis shows that patients with chromosomal numerical abnormality and balanced translocations should be treated early to prevent transition to AML. Further study of this case will reveal the molecular mechanism of MDS-to-AML transformation and identify new leukemic fusion genes.

Rare Case of Diffuse Large B-Cell Lymphoma Mimicking Acute Monocytic Leukemia, Associated with Complex Karyotype

OBJECTIVE

Diffuse Large B-Cell Lymphoma (DLBCL), NOS, constitutes 25-35% of adult non-Hodgkin lymphomas in developed countries, and a higher percentage in developing countries; older people are prone to the disease. Three frequent morphological variants have been recognized, including centroblastic, immunoblastic, and anaplastic variants. However, there are still other rare morphological variants of DLBCL, presenting challenge in diagnosis and treatment.

CASE PRESENTATION

A 62-year-old woman sought medical attention with a previous 6-month history of intermittent fever and leukocytosis. Bone marrow (BM) aspiration presented AML with acute monocytic leukemia-like morphologic features. The results of the immunophenotypic analysis suggested mature B cell lymphoma without obvious subtype characteristics. Lymph node biopsy indicated DLBCL of non-germinal centre B-cell subtype (n-GCB). Cytogenetic analysis of the BM cells revealed a 46,XX, trp(1)(q21q32),del(7)(q32q36),t(9;14)(p13;q32) [4]/46,XX [16] karyotype. The patient was diagnosed with EBV-positive DLBCL, NOS based on the combination of lymph node biopsy, clinical, cytological, immunophenotypic, and cytogenetic analyses.

CONCLUSION

To date, no case reports of a patient diagnosed with DLBCL mimicking acute monocytic leukemia with complex karyotype have been reported. We present the case given its rarity, easy misdiagnosis, and poor prognosis. The case highlights the importance of awareness about the rare morphological variant to laboratory staff and hematologists.

Telomere and Centromere Staining Followed by M-FISH Improves Diagnosis of Chromosomal Instability and Its Clinical Utility

Dicentric chromosomes are a relevant marker of chromosomal instability. Their appearance is associated with telomere dysfunction, leading to cancer progression and a poor clinical outcome. Here, we present Telomere and Centromere staining followed by M-FISH (TC+M-FISH) for improved detection of telomere dysfunction and the identification of dicentric chromosomes in cancer patients and various genetic syndromes. Significant telomere length shortening and significantly higher frequencies of telomere loss and deletion were found in the peripheral lymphocytes of patients with cancer and genetic syndromes relative to similar age-matched healthy donors. We assessed our technique against conventional cytogenetics for the detection of dicentric chromosomes by subjecting metaphase preparations to both approaches. We identified dicentric chromosomes in 28/50 cancer patients and 21/44 genetic syndrome patients using our approach, but only 7/50 and 12/44, respectively, using standard cytogenetics. We ascribe this discrepancy to the identification of the unique configuration of dicentric chromosomes. We observed significantly higher frequencies of telomere loss and deletion in patients with dicentric chromosomes (p < 10⁻⁴). TC+M-FISH analysis is superior to classical cytogenetics for the detection of chromosomal instability. Our approach is a relatively simple but useful tool for documenting telomere dysfunction and chromosomal instability with the potential to become a standard additional diagnostic tool in medical genetics and the clinic.

Cytogenetics of Blastic Plasmacytoid Dendritic Cell Neoplasm: Chromosomal Rearrangements and DNA Copy-Number Alterations

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a skin-tropic hematopoietic malignancy. Approximately 60% of cases with analyzable karyotyping results show complex karyotypes. Losses are more frequently found than copy-number gains. Recurrently deleted regions include tumor suppressor genes. No specific chromosomal abnormalities have been demonstrated in BPDCN, but genomic rearrangements involving the MYB family genes and MYC were identified. One-third of cases of BPDCN harbor the 8q24 rearrangement, most frequently with 6p21 harboring RUNX2, which is associated with immunoblastoid cytomorphology and MYC expression. MYB rearrangement is detected in 20% of patients with BPDCN. We review copy-number alterations and chromosomal rearrangements.

Microfluidic Device for On-Chip Immunophenotyping and Cytogenetic Analysis of Rare Biological Cells

The role of circulating plasma cells (CPCs) and circulating leukemic cells (CLCs) as biomarkers for several blood cancers, such as multiple myeloma and leukemia, respectively, have recently been reported. These markers can be attractive due to the minimally invasive nature of their acquisition through a blood draw (i.e., liquid biopsy), negating the need for painful bone marrow biopsies. CPCs or CLCs can be used for cellular/molecular analyses as well, such as immunophenotyping or fluorescence in situ hybridization (FISH). FISH, which is typically carried out on slides involving complex workflows, becomes problematic when operating on CLCs or CPCs due to their relatively modest numbers. Here, we present a microfluidic device for characterizing CPCs and CLCs using immunofluorescence or FISH that have been enriched from peripheral blood using a different microfluidic device. The microfluidic possessed an array of cross-channels (2-4 µm in depth and width) that interconnected a series of input and output fluidic channels. Placing a cover plate over the device formed microtraps, the size of which was defined by the width and depth of the cross-channels. This microfluidic chip allowed for automation of immunofluorescence and FISH, requiring the use of small volumes of reagents, such as antibodies and probes, as compared to slide-based immunophenotyping and FISH. In addition, the device could secure FISH results in <4 h compared to 2-3 days for conventional FISH.

Chromosomal microarray analysis in prenatal diagnosis: ethical considerations of the Belgian approach

Detection of genetic aberrations in prenatal samples, obtained through amniocentesis or chorion villus biopsy, is increasingly performed using chromosomal microarray (CMA), a technique that can uncover both aneuploidies and copy number variants throughout the genome. Despite the obvious benefits of CMA, the decision on implementing the technology is complicated by ethical issues concerning variant interpretation and reporting. In Belgium, uniform guidelines were composed and a shared database for prenatal CMA findings was established. This Belgian approach sparks discussion: it is evidence-based, prevents inconsistencies and avoids parental anxiety, but can be considered paternalistic. Here, we reflect on the cultural and moral bases of the Belgian reporting system of prenatally detected variants.

Clinical, cytogenetic and molecular genetic characterization of a tandem fusion translocation in a male Holstein cattle with congenital hypospadias and a ventricular septal defect

Hypospadias, disorder of sex development (DSD), is a sporadic congenital abnormality of the genital region in male ruminants, which is characterized by a non-fused urethra during fetal development. Detailed clinical examination classified the hypospadias phenotype of a male Holstein calf studied here as the perineal type. In combined use of cytogenetic analysis and whole genome sequencing, a non-mosaic, pseudo-monosomy 59, XY + tan(18;27) was detected. This chromosomal aberration had its origin in a tandem fusion translocation of the bovine autosomes (BTA) 18 and 27 with an accompanying loss of genomic sequences mainly in the distal end of BTA 18 and the proximal end of BTA 27. The resulting phenotype included hypospadias, growth retardation and ventricular septal defect.

Analysis of Meiosis in Nonmodel Tropical Plants: The Case of Carica papaya Linn

To develop plants that are more tolerant to drought, marginal soil fertility, and diseases and that satisfy demands for high yield, new cultivars of the tropical fruit papaya (Carica papaya L.) are needed. Nonetheless, in many cases, these traits are available in only wild relatives found throughout Latin America. Understanding meiotic progression may facilitate the introgression of desirable traits into commercial cultivars that maintain high fertility. In this protocol, we describe a practical and simple method to effectively isolate male meiocytes in order to document the behavior of papaya meiotic chromosomes.

Cytological Techniques to Study Cytomixis in Plant Male Meiosis

In this chapter we describe cytological techniques to study cytomixis, a process of nuclear migration between plant cells, in squashed plant male meiocytes of Nicotiana tabacum and Secale cereale. To perform immunostaining or fluorescence in situ hybridization (FISH) on meiotic cells involved in cytomixis common protocols are modified. During preparation of specimens for subsequent cytological analysis, it is necessary not only to make DNA and proteins accessible to DNA probes and antibodies, but also to preserve cell cytoplasm. There are also some important modifications in the protocols applied for meiocytes of different plant species. Here we describe protocols for immunostaining and FISH in rigid tobacco male meiocytes with dense cytoplasm and thick callose wall, that tolerate hard squashing, and in soft rye male meiocytes, that are easily damaged upon squashing, both to study cytomixis.

CYTOGENETIC BIODOSIMETRY OF ACCIDENTAL EXPOSURES IN THE LONG TERMS AFTER IRRADIATION

The group of radiation victims who had received radiation injures similar to those of Chernobyl accident victims was evaluated in terms of retrospective cytogenetic biodosimetry in the long term period of from 17 y up to 50 y after irradiation. Based on the existing results of the long-term cytogenetic examination of the victims injured after the Chernobyl accident, an original method was developed. This method of retrospective dose recovery was based on the use of a special computer program, the time elapsed after irradiation and the frequency of atypical chromosomes. Both patient groups were examined using conventional cytogenetic analysis. The new method of a retrospective biodosimetry was tested on the non-Chernobyl group. As a result the multiple regression equations which included frequency atypical chromosomes produced better results because the majority of the estimates of the retrospective doses fell into the 95%-prediction intervals for the reference group of the Chernobyl victims.

THE PROJECT OF ANOTHER LOW-COST METAPHASE FINDER (SECOND REPORT-APPLICATION OF ARTIFICIAL INTELLIGENCE)

Biological dosimetry is used to estimate individual absorbed radiation dose by quantifying an appropriate biological marker. The most popular gold-standard marker is the appearance of dicentric chromosomes in metaphase. The metaphase finder is a tool for biological dosimetry that finds metaphase cells on glass slides. The author and a software company have designed a new system and are now preparing to produce the system commercially. The metaphase finder consists of an automated microscope, a camera, and a computer. To enhance the accuracy of the system, an artificial intelligence (AI) with deep learning was tested. A total of 1709 images of the metaphase finder detected as 'metaphases' were read into a nine-layer artificial neural network to detect true metaphases. A total of 456 images were used for training, and the rest of the images were used for validation. The accuracy of AI was 0.89 for metaphases and 0.90 for non-metaphases.

RADIATION DOSE ESTIMATION BY COMPLETELY AUTOMATED INTERPRETATION OF THE DICENTRIC CHROMOSOME ASSAY

Accuracy of the automated dicentric chromosome (DC) assay relies on metaphase image selection. This study validates a software framework to find the best image selection models that mitigate inter-sample variability. Evaluation methods to determine model quality include the Poisson goodness-of-fit of DC distributions for each sample, residuals after calibration curve fitting and leave-one-out dose estimation errors. The process iteratively searches a pool of selection model candidates by modifying statistical and filter cut-offs to rank the best candidates according to their respective evaluation scores. Evaluation scores minimize the sum of squared errors relative to the actual radiation dose of the calibration samples. For one laboratory, the minimum score for the curve fit residual method was 0.0475 Gy2, compared to 1.1975 Gy2 without image selection. Application of optimal selection models using samples of unknown exposure produced estimated doses within 0.5 Gy of physical dose. Model optimization standardizes image selection among samples and provides relief from manual DC scoring, improving accuracy and consistency of dose estimation.