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PubMed2026

Cytogenetic Diversity of Variant Philadelphia Translocations in Chronic Myeloid Leukemia.

INTRODUCTION: Chronic myeloid leukemia (CML) is a disease characterized by Philadelphia (Ph) translocations. These translocations can be classical or variant. The structural features and diagnostic implications of variant Philadelphia translocations remain incompletely defined, and they display considerable cytogenetic heterogeneity. METHODS: In this retrospective study, variant Ph translocations identified by conventional cytogenetic analysis and fluorescence in situ hybridization (FISH) were systematically classified among 639 patients diagnosed with CML. A total of 35 patients with variant Ph translocations were included in the analysis. Molecular follow-up data, when available, were assessed using RT-qPCR analyses in a subset of patients. RESULTS: Chromosome analysis revealed 2 simple and 33 complex variant Ph translocations. FISH analysis, performed in 20 patients, identified deletions involving BCR, ABL1, or both in a limited number of cases. Additional chromosomal abnormalities and secondary translocations accompanied variant Ph translocations in four patients. The partner chromosomes involved in variant Ph translocations showed marked diversity, involving multiple chromosomal loci. CONCLUSION: Variant Philadelphia chromosome translocations in CML exhibit substantial cytogenetic diversity, reflecting the complexity of their underlying genomic architecture. The rarity and heterogeneity of these rearrangements complicate their classification and interpretation in routine diagnostic practice. Descriptive reporting of variant Ph translocations may contribute to a better understanding of their diagnostic complexity and support more accurate cytogenetic interpretation in CML.

Humans↗

PubMed2026

Highly Contiguous Is Not Chromosomally Accurate: Integrated Cytogenetic and Genomic Mapping in Two Turtle Genome.

High-quality genome assemblies are essential for robust research across biological and medical fields. Assembly errors can have far-reaching consequences for downstream analyses, including gene annotation and the inference of synteny. In contrast to the rapid growth of genomic data volume, there is a notable lag in the integration of chromosome-level assemblies with cytogenetic data. We conducted the first direct genome-to-genome comparison, integrating comparative chromosome painting, the alignment of chromosome-specific probes to available genome assemblies, and synteny-based comparison of independent chromosome-level assemblies of the loggerhead sea turtle (Caretta caretta, 2n = 56) and the red-eared slider (Trachemys scripta elegans, 2n = 50). Using two independent sets of flow-sorted chromosome-specific probes in cross-species hybridizations, together with the sequencing and mapping of chromosome-derived DNA libraries, we assigned assembled scaffolds to all physical chromosomes of both species. In C. caretta, chromosomal assignments and genome-wide synteny were fully consistent with the published assembly, except for the reduced sizes of two microchromosome scaffolds, which we attribute to under-representation of repetitive DNA. In contrast, in T. s. elegans, cytogenetic validation of the assemblies revealed a false rearrangement compared to a missed one. Our results show that even highly contiguous vertebrate genome assemblies can misrepresent chromosome structure. When cytogenetic analyses reveal such inaccuracies, updated reference genomes should be generated for widely studied species to enable accurate inference of karyotype evolution and downstream comparative genomic analyses.

FISH↗

PubMed2026

Three-Year Experience of Cytogenetic and Molecular Genetic Evaluation in Patients With Disorders of Sex Development at a Tertiary Care Centre in Eastern India.

OBJECTIVES: Disorders of sex development (DSD) include a range of conditions in which chromosomal, gonadal, or anatomical sex deviates from the typical developmental pathway. The diagnostic approach to DSD has shifted from karyotyping to molecular genetic tools. This study evaluated the clinical presentation, cytogenetic spectrum, and diagnostic utility of conventional and advanced molecular genetic investigations in patients with suspected DSD managed at a tertiary care facility in Eastern India over a three-year period. METHODS: A retrospective observational study was conducted at the Genetics Laboratory of a tertiary care teaching hospital in Eastern India. Consecutive patients with clinically suspected DSD referred between January 2022 and December 2024 were included. Demographic and clinical data were obtained from referral records, and peripheral blood samples were analysed using standard G-banded karyotyping according to the International System for Human Cytogenomic Nomenclature (ISCN 2020). Fluorescence in situ hybridisation (FISH), chromosomal microarray analysis (CMA), and whole-genome sequencing (WGS) were selectively performed in cases with inconclusive cytogenetic findings, suspected structural chromosomal abnormalities, or complex phenotypes. RESULTS: A total of 98 suspected DSD cases were evaluated during the study period. The most frequent chromosomal constitution was 46,XY DSD (37, 37.8%), followed by 46,XX DSD (30, 30.6%) and sex chromosome DSD (21, 21.4%). Culture failure occurred in 10 (10.2%) samples. Advanced genetic techniques, including FISH, CMA, and WGS, improved diagnostic clarification in selected complex cases. CONCLUSION: This experience highlights the importance of integrating contemporary high-resolution technologies with conventional cytogenetics to enhance the assessment, counselling, and treatment of individuals with DSD.

chromosomal analysis↗

PubMed2025

Cytogenetic and molecular characterization of an atypical ETP-ALL case with BCL2 dependency: therapeutic implications for Venetoclax use.

BACKGROUND: Early T-cell precursor acute lymphoblastic leukemia (ETP-ALL) is a rare, high-risk subtype of T-ALL characterized by distinctive immunophenotypic and genomic features. It is often associated with induction failure and frequent relapses. Despite recent advances in its molecular characterization, the prognosis remains dismal, and effective targeted therapies are limited. METHODS AND RESULTS: We report a pediatric, multi-refractory ETP-ALL case with novel cytogenetic alterations, including a 4q deletion and a t(16;18)(q24;q21) translocation. Molecular profiling revealed progressive activation of the BCL2 pathway and disruption of Th17-related immune markers. Ex vivo sensitivity assays performed at different disease stages demonstrated increasing BCL2 dependency. Based on these findings, venetoclax was administered on a compassionate-use basis, resulting in rapid hematologic recovery and a marked reduction in blast percentage. CONCLUSIONS: This case highlights the role of clonal evolution and immune deregulation in accompanying BCL2 addiction in relapsed ETP-ALL. Altogether, our findings underscore the therapeutic potential of venetoclax in refractory pediatric ETP-ALL cases with progressive BCL2 dependency.

Humans↗

PubMed2025

Cytogenetics and genomics analysis of cold-hardy perennial wheatgrass: insights into agronomic performance, chromosome composition, and gene expression.

Intermedium wheatgrass (Thinopyrum intermedium), a perennial species with extensive root systems and high tolerance to cold, drought, and salinity, is a valuable genetic resource for the development of perennial crops. Over a decade-long selection process, two cold-hardy perennial wheatgrass lines were developed by crossing wheat-Thinopyrum partial amphiploids with Th. intermedium. These lines inherited key traits from Th. intermedium, including plant stature, spike morphology, and postharvest regrowth. Transcriptome-based single-nucleotide polymorphism tracing and sequential multicolor genomic in situ hybridization analyses revealed variations in the chromosome compositions of the perennial wheatgrass lines. The introgression of wheat chromosomes enhanced grain weight and size, while preserving the cold-hardy, perennial characteristics of the wheatgrass lines compared to Th. intermedium. Genome-wide gene expression was generally suppressed in the wheatgrass lines relative to Th. intermedium, particularly in conserved genes. This suppression was especially pronounced in genes involved in cell division and DNA repair pathways. In contrast, genes associated with cold tolerance and the water stress response were upregulated. We identified eight cold-tolerance genes in the Th. intermedium chromosomes and validated three of them, Thint.J05G452200, Thint.J05G452300, and Thint.V05G408900, using qRT-PCR. These genes encode proteins associated with cold tolerance and are potential candidates for further functional validation. Additionally, three chromosomes from homoeologous group 6 were introgressed, carrying six genes potentially associated with superior grain traits. Among them, TraesCS6D02G287800, which encodes a specific protein, exhibited high expression levels in both wheatgrass lines, suggesting its critical role in enhancing grain traits. Our results indicate that the suppression of grass gene expression, likely due to the introgression of wheat chromosomes and the upregulation of pathways related to cold tolerance and overwintering ability, contributes to the adaptive features of the wheatgrass lines. This study provides a genomic foundation for understanding gene expression regulation in distant hybrid progeny and offers valuable insights for designing new breeding strategies for perennial wheat or wheatgrass.

Chromosomes, Plant↗

PubMed2024

Prenatal diagnosis and molecular cytogenetic analysis of pure chromosome 10p15.3 microdeletion using chromosomal microarray analysis.

BACKGROUND: The literature contains exceedingly limited reports on chromosome 10p15.3 microdeletions. In the present study, two cases of fetuses with pure terminal 10p15.3 microdeletion syndrome in a Chinese population were examined, with the objective of enhancing understanding of the genotype-phenotype correlation associated with 10p15.3 microdeletions. METHODS: Two fetuses with chromosome 10p15.3 microdeletion were identified from a cohort of 5,258 cases undergoing amniocentesis. Karyotyping and chromosomal microarray analysis (CMA) was conducted to assess chromosomal abnormalities and detect copy number variations (CNVs) within the families, respectively. RESULTS: In Family 1, the fetus exhibited a 556.2-Kb deletion in the 10p15.3 region, encompassing OMIM genes such as DIP2C and ZMYND11, and presented with increased nuchal translucency on prenatal ultrasound examination. Parental CMA analysis revealed that the 10p15.3 microdeletion was inherited from the father, who displayed mild language impairment. In Family 2, a comparable 10p15.3 microdeletion was identified in a fetus presenting with asymmetric butterfly vertebrae at T10 and T12, along with mild scoliosis of the spine. Family 1 elected to terminate the pregnancy, while Family 2 chose to continue. At a follow-up conducted at one year and eight months, the child demonstrated delays in both speech and motor development. CONCLUSION: The present study is the first to report two cases of pure terminal chromosome 10p15.3 microdeletion syndrome in fetuses, offering valuable insights for the prenatal diagnosis of 10p15.3 microdeletion syndrome. Further, it is the first to describe mild clinical features, specifically limited to language impairment, in a patient with 10p15.3 microdeletion syndrome.

Female↗

PubMed2026

Research Progress in the Cytogenetics of Sweetpotato and Its Wild Relatives.

Cultivated sweetpotato (Ipomoea batatas (L.) Lam.), a hexaploid (2n = 6x = 90) crop, is the most economically important species within the morning glory genus Ipomoea (Convolvulaceae). Fourteen diploid Ipomoea species and several polyploid accessions have been confirmed to be closely related to sweetpotato, often termed its wild relatives. These wild species harbor abundant elite genes beneficial to sweetpotato improvement and thereby serve as indispensable germplasm reservoirs for breeding programs. In addition, several wild taxa are proposed as potential ancestors of domesticated sweetpotato. Nevertheless, the evolutionary origin and genomic architecture of cultivated sweetpotato have not yet been fully resolved. Cytological investigations, particularly chromosome karyotyping and meiotic pairing analyses, have been pivotal in unravelling the genomic architecture and evolutionary trajectories of polyploid taxa. Herein, we systematically summarize advances in chromosome counting, genome size, karyotyping, and meiotic pairing research on sweetpotato and its wild relatives.

Ipomoea↗

PubMed2025

Genomic Alterations in Multiple Myeloma: A Comprehensive Landscape.

UNLABELLED: Multiple myeloma (MM) is a biologically heterogeneous plasma cell malignancy in which cytogenetic abnormalities play a key role in disease prognosis. This study evaluates the spectrum of genomic aberrations in newly diagnosed multiple myeloma (NDMM) patients, with a focus on high-risk cytogenetic profiles, including double-hit (DHMM), and triple-hit multiple myeloma (THMM). This is a retrospective analysis of NDMM patients, reviewing clinical and laboratory data for baseline characteristics, cytogenetics, therapy, and outcomes. Patients were categorized based on the cytogenetic abnormalities. Double-hit MM was defined by the coexistence of two high-risk abnormalities and triple-hit MM was defined by coexistence of three or more high-risk abnormalities. Survival outcomes were assessed using Kaplan-Meier analysis and Cox regression models using SigmaPlot (version 15). A total of 314 NDMM cases (205 Male: 109 Female; median age 58 years) enrolled between 2014 and 2021 were evaluated. Using the Revised International Staging System (R2-ISS), most patients were in stage 2 (41.1%) and stage 3 (38.2%). Cytogenetic analysis revealed one or more high-risk abnormalities in 43% of cases. Among the high-risk group, one, two and three or more high-risk abnormalities were observed in 89 (28%), 35 (11%), and 11 (4%) patients, respectively. THMM cases exhibited the poorest outcomes [median overall survival (OS):7 months], in comparison to DHMM (OS: 33 months), SHMM (OS: 40 months), and patients without high-risk features (OS: 60 months). Cox regression analysis confirmed that THMM patients had a 3.6-fold increased risk of death (HR: 3.677; 95% CI: 2.219-7.915; p < 0.001) and 4-fold increased risk of progression (HR: 4.191; 95% CI: 1.897-7.126; p < 0.001) compared to patients without any high-risk abnormalities. Among 67 patients undergoing autologous stem cell transplant (ASCT), high risk abnormalities were significantly associated with shorter OS (HR: 2.409; 95% CI: 1.094-5.291; p = 0.029, 111 months for ASCT without high-risk vs. 78 months for ASCT with high- risk abnormalities) and shortened PFS (HR: 2.379; 95% CI: 1.285-4.403; p = 0.006, 85 months for ASCT without high-risk vs. 34 months with high-risk abnormalities). Double and triple-hit MM constitute 14.6% of NDMM cases, indicating poor survival and early disease progression. Comprehensive cytogenetic profiling at diagnosis and post-ASCT has the potential to improve risk stratification and guide individualized treatment strategies for high-risk MM patients. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at https://doi.org/10.1007/s12288-025-02284-5.

Cytogenetic↗

PubMed2005

Construction of a 2-Mb resolution BAC microarray for CGH analysis of canine tumors.

Recognition of the domestic dog as a model for the comparative study of human genetic traits has led to major advances in canine genomics. The pathophysiological similarities shared between many human and dog diseases extend to a range of cancers. Human tumors frequently display recurrent chromosome aberrations, many of which are hallmarks of particular tumor subtypes. Using a range of molecular cytogenetic techniques we have generated evidence indicating that this is also true of canine tumors. Detailed knowledge of these genomic abnormalities has the potential to aid diagnosis, prognosis, and the selection of appropriate therapy in both species. We recently improved the efficiency and resolution of canine cancer cytogenetics studies by developing a small-scale genomic microarray comprising a panel of canine BAC clones representing subgenomic regions of particular interest. We have now extended these studies to generate a comprehensive canine comparative genomic hybridization (CGH) array that comprises 1158 canine BAC clones ordered throughout the genome with an average interval of 2 Mb. Most of the clones (84.3%) have been assigned to a precise cytogenetic location by fluorescence in situ hybridization (FISH), and 98.5% are also directly anchored within the current canine genome assembly, permitting direct translation from cytogenetic aberration to DNA sequence. We are now using this resource routinely for high-throughput array CGH and single-locus probe analysis of a range of canine cancers. Here we provide examples of the varied applications of this resource to tumor cytogenetics, in combination with other molecular cytogenetic techniques.

Animals↗

PubMed2026

Mapping the de-implementation of traditional diagnostic tests in pediatric acute lymphoblastic leukemia.

INTRODUCTION: Advances in cancer diagnostics raise questions about when and how to de-implement traditional approaches; however, these processes remain poorly described. At St. Jude Children's Research Hospital (SJCRH), routine conventional cytogenetics for pediatric acute lymphoblastic leukemia (ALL) diagnosis was de-implemented in 2018 following adoption of clinical genomics. This study aimed to map this process to inform future diagnostic de-implementation initiatives. METHODS: Interviews were conducted with SJCRH staff involved or impacted by cytogenetics de-implementation. Data were analyzed using thematic and rapid qualitative analysis informed by the Consolidated Framework for Implementation Research. Member-checking was used to verify and refine process maps, which were subsequently reviewed by an external expert panel, representing diverse settings, through focus group discussions. RESULTS: Thirteen SJCRH clinicians participated. De-implementation was described as successful, with no negative impact on patient outcomes. Decision-making began with internal correlation studies that demonstrated superior diagnostic performance of clinical genomics. De-implementation was viewed as a natural evolution that improved molecular classification, resource allocation, and workflow efficiency. Perceived risks included loss of cytogenetics competency, delayed turnaround time, and career insecurity, all addressed institutionally. Lessons learned highlighted the importance of deliberate discussion about logic and evidence supporting de-implementation. Fifteen external experts offered suggestions to improve process map generalizability, highlighting institutional- and system-level considerations. CONCLUSION: De-implementation of cytogenetics in ALL in favor of clinical genomics was successful at SJCRH. This study offers an example of diagnostic de-implementation in cancer care and proposes a structured approach to guide future efforts. De-implementation should be considered alongside introduction of novel diagnostic approaches.

cancer diagnostics↗

PubMed2025

Optical Genome Mapping in Myelodysplastic Syndromes: Clinical Value and Limitations Derived From a Cohort of 236 Patients.

Identification of cytogenetic abnormalities is critical for the classification and risk stratification of myelodysplastic syndromes (MDS). Optical genome mapping (OGM) is an emerging cytogenomic platform that enables high-resolution genome-wide cytogenetic analysis. We analyzed bone marrow specimens of 236 MDS patients, 149 newly diagnosed and 87 with relapsed/refractory disease, using OGM, conventional karyotyping, and next-generation sequencing analysis. OGM and karyotyping showed concordant results in 68% of cases, including 34% with normal findings by both assays. OGM provided additional information in 27% of patients. Common abnormalities detected exclusively by OGM included chromoanagenesis (n = 33), KMT2A partial tandem duplication (n = 7), and MECOM rearrangement (n = 4). These OGM findings led to disease reclassification and/or changes in risk stratification in 14 patients (9.4%) with newly diagnosed MDS. In contrast, OGM failed to detect small clones or subclones in 5% of patients, resulting in risk group changes in 2% of newly diagnosed MDS patients. We conclude that OGM enhances the cytogenetic assessment of MDS in approximately 25% of patients and leads to a change in disease classification and/or risk stratification in approximately 10% of patients. However, low sensitivity for detecting small clones or subclones remains a limitation of OGM.

Humans↗

PubMed2026

Genomic risk profiling in advanced maternal age: a Tamil Nadu prenatal study.

BACKGROUND: Advanced maternal age (AMA; > = 35 years) is associated with increased fetal chromosomal risk and is an important indication for invasive prenatal diagnosis. This study evaluates karyotyping and chromosomal microarray analysis (CMA) findings among AMA pregnancies in Tamil Nadu, India. METHODS: In this prospective observational study, 2,200 pregnant women aged ≥35 years who underwent amniocentesis between July 2020 and June 2021 were enrolled. Conventional karyotyping was performed in all cases. CMA was performed as a reflex or complementary test when predefined clinical or cytogenetic criteria were present, including ultrasound abnormalities, high-risk screening/NIPT results, abnormal or uncertain karyotype findings, prior adverse pregnancy history suggestive of genetic etiology, parental chromosomal abnormalities, or patient request after counseling. RESULTS: Numerical chromosomal abnormalities were detected in 76/2200 cases (3.5%), and structural abnormalities were detected in 9/2200 cases (0.4%). The total abnormal cytogenetic yield was therefore 85/2200 cases (3.9%) when numerical and structural abnormalities were considered together. Age-stratified analysis showed an increasing trend in chromosomal abnormalities with advancing maternal age, reaching 10.4% in women aged > = 43 years. Cases with additional clinical indications showed higher abnormality rates than simple AMA. CMA was performed in selected cases and contributed to characterization of clinically relevant genomic abnormalities, supporting its role in indicated high-risk AMA pregnancies. CONCLUSION: The Tamil Nadu cohort provides regional evidence on age-stratified cytogenetic risk in AMA pregnancies and supports the use of clearly defined criteria for integrating CMA with conventional karyotyping in prenatal diagnosis.

India↗

PubMed2026

Mitotic karyotyping and FISH mapping of the gender-specific locus indicate an advanced XY system in Hippophae rhamnoides.

Hippophae rhamnoides ssp. turkestanica, a subdioecious plant inhabiting the cold desert of the Indian Himalaya, has gained immense recognition for its nutritional and medicinal values. In recent years, the plant species has proven to be a suitable system to understand the evolution of dioecy. Despite its biological significance, the cytogenetics of this dioecious plant is unclear due to various conflicting accounts of its X-Y chromosome system, particularly the length of Y-chromosome. In this study, we resolved these ambiguities through comprehensive cytogenetic analyses across diverse western Himalayan populations. Using morphometric analysis and fluorescence in situ hybridization (FISH) with a gender-specific marker (HRMSSR), we confirmed homomorphic XX chromosomes in females and heteromorphic sex-chromosomes in males with a notably smaller Y-chromosome. The investigation also revealed a predominant somatic chromosome number of 2n = 24, although minor deviations (2n = 18, 20, 22) appeared at the seed level. These findings highlight an evolutionarily advanced sex-chromosome system. This first detailed cytogenetic investigation of Himalayan Seabuckthorn provides critical insights into the chromosomal architecture, laying a crucial foundation for future evolutionary, genomic, and conservation studies in the species.

Chromosome Mapping↗

PubMed2026

Unraveling evolutionary relationships in the Sida generic alliance (Malvaceae, Malvoideae): a phylogenetic and cytotaxonomic overview.

Sida (Malvaceae), the largest Malveae-Abutilinae member, has poorly defined morphological limits which overlaps with 11 phylogenetically closely related genera that comprises the "Sida generic alliance". The 12 genera are distributed in the tropics especially in Brazil where one third of its species diversity is found. Evolutionary relationships within Sida generic alliance remain unresolved due to morphological convergence, limited taxon sampling, and lack of integrative approaches including cytogenetic data. We reconstructed the phylogeny of Sida and allied genera using a multilocus dataset (nuclear ITS and seven plastid loci) including 193 species classified in 19 genera and analyzed chromosome evolution using cytogenetic data (chromosome number) for 79 species of the 19 genera. The phylogeny recovered seven clades-Abutilon, Bakeridesia, Callianthe, Gaya, and three Sida clades (I-III)-and confirmed the polyphyly of Sida, the largest genera. We detected reticulate evolution, with incongruence between nuclear and plastid topologies. Chromosome number ranged from 2n = 12 to 60 and represented synapomorphies for most clades. Ancestral character reconstruction indicated that ascending dysploidy and polyploidy predominated in karyotype evolution of Sida and allied genera. Our results reveal taxonomic incongruence in current classifications probably related to reticulate evolution. A generic-level taxonomic revision is necessary and should rely on integrated phylogenetic and karyotypic evidence. This study provides a framework for phylogenetic systematics and emphasizes the role of Brazil as a hotspot for plant genomic research.

Phylogeny↗

PubMed2022

High early death rates, treatment resistance, and short survival of Black adolescents and young adults with AML.

Survival of patients with acute myeloid leukemia (AML) is inversely associated with age, but the impact of race on outcomes of adolescent and young adult (AYA; range, 18-39 years) patients is unknown. We compared survival of 89 non-Hispanic Black and 566 non-Hispanic White AYA patients with AML treated on frontline Cancer and Leukemia Group B/Alliance for Clinical Trials in Oncology protocols. Samples of 327 patients (50 Black and 277 White) were analyzed via targeted sequencing. Integrated genomic profiling was performed on select longitudinal samples. Black patients had worse outcomes, especially those aged 18 to 29 years, who had a higher early death rate (16% vs 3%; P=.002), lower complete remission rate (66% vs 83%; P=.01), and decreased overall survival (OS; 5-year rates: 22% vs 51%; P<.001) compared with White patients. Survival disparities persisted across cytogenetic groups: Black patients aged 18 to 29 years with non-core-binding factor (CBF)-AML had worse OS than White patients (5-year rates: 12% vs 44%; P<.001), including patients with cytogenetically normal AML (13% vs 50%; P<.003). Genetic features differed, including lower frequencies of normal karyotypes and NPM1 and biallelic CEBPA mutations, and higher frequencies of CBF rearrangements and ASXL1, BCOR, and KRAS mutations in Black patients. Integrated genomic analysis identified both known and novel somatic variants, and relative clonal stability at relapse. Reduced response rates to induction chemotherapy and leukemic clone persistence suggest a need for different treatment intensities and/or modalities in Black AYA patients with AML. Higher early death rates suggest a delay in diagnosis and treatment, calling for systematic changes to patient care.

Adolescent↗

PubMed2026

Tandem Double Inversion Resolves the Structural Paradox Underlying Recurrent KAT6A::NCOA2 Fusion in Acute Myeloid Leukemia.

The KAT6A::NCOA2 (formerly MOZ::TIF2) fusion is an extremely rare recurrent genetic abnormality in acute myeloid leukemia (AML), with only nine cases reported to date. It has consistently been associated with inv(8)(p11q13). However, the genomic mechanism underlying this fusion has remained unresolved. Because both KAT6A and NCOA2 are transcribed in the same reverse orientation on chromosome 8, a simple inversion is structurally insufficient to generate a transcriptionally competent fusion transcript, creating a long-standing cytogenetic paradox. We analyzed an AML case harboring a KAT6A::NCOA2 fusion using targeted genomic profiling and breakpoint-level validation. In addition to the canonical KAT6A::NCOA2 fusion, sequencing identified an unexpected MTFR1::KAT6A rearrangement. Since MTFR1 is located between KAT6A and NCOA2 on chromosome 8, we hypothesized a complex intrachromosomal rearrangement. Genomic breakpoint analysis revealed that the fusion was generated not by a single inv(8), but by two adjacent intrachromosomal inversions forming a tandem double inversion. This rearrangement reoriented genomic segments to place KAT6A and NCOA2 in a transcriptionally compatible configuration, enabling fusion formation. These findings resolve the structural paradox of KAT6A::NCOA2-positive AML by demonstrating that a cytogenetically apparent inv(8)(p11q13) can conceal a tandem double-inversion architecture that reorients KAT6A and NCOA2 into a transcriptionally compatible configuration.

Humans↗

PubMed2026

KIT and FLT3-ITD mutations do not predict outcomes in pediatric core-binding factor acute myeloid leukemia: findings from the C-HUANAN-AML-15 multicenter cohort study.

Although core-binding factor acute myeloid leukemia (CBF-AML) is generally considered a favorable-risk subtype in children, disease relapse remains a significant concern. The prognostic relevance of co-occurring mutations, particularly KIT and FLT3-ITD, remains debatable, and treatment intensity may modulate their impact. This multicenter analysis included 289 children (< 14 years) with newly diagnosed CBF-AML enrolled in the C-HUANAN-AML-15 study (2015-2023). KIT and FLT3-ITD mutations were identified via cytogenetic analysis and targeted sequencing. Measurable residual disease (MRD) was evaluated by multiparameter flow cytometry (MFC) and quantitative polymerase chain reaction (PCR) following induction chemotherapy. Survival analyses were performed using Kaplan-Meier and Cox regression methods. This multicenter analysis included 289 children (< 14 years) with newly diagnosed CBF-AML enrolled in the C-HUANAN-AML-15 study (2015-2023). KIT and FLT3-ITD mutations were identified via cytogenetic analysis and targeted sequencing. Measurable residual disease (MRD) was evaluated by multiparameter flow cytometry (MFC) and quantitative polymerase chain reaction (PCR) following induction chemotherapy. Survival analyses were performed using Kaplan-Meier and Cox regression methods. KIT mutations were detected in 103 patients (35.6%), predominantly involving exon 17 (69.9%), and were associated with extramedullary disease, sex chromosome loss, and trisomy 22. No significant differences in 5-year event-free survival (EFS), overall survival (OS), or cumulative incidence of relapse (CIR) were observed between patients with and without KIT mutations. FLT3-ITD mutations (5.5% of patients) did not adversely affect outcomes. Neither mutation independently predicted survival. MRD positivity (MFC-MRD ≥ 0.1%) after the second induction cycle strongly predicted inferior EFS and OS and higher CIR, with corresponding results observed for molecular MRD and parallel findings for PCR-based MRD. In this large multicenter cohort, KIT and FLT3-ITD mutations did not adversely affect the prognosis of pediatric CBF-AML treated according to the C-HUANAN-AML-15 protocol. MRD after induction was the most powerful predictor of relapse and survival, underscoring its importance for risk stratification in future pediatric AML trials.

Humans↗

PubMed2026

Satellite DNA evolution in Tytonidae (Aves: Strigiformes): dynamic repeat landscapes despite conserved karyotypes.

The elevated chromosome numbers observed in Tytonidae relative to the putative ancestral avian karyotype suggest that lineage-specific chromosomal fissions may have played an important role in the evolutionary history of this family. Here, we provide the first cytogenetic characterization of the American barn owl (Tyto furcata) and performs a comparative repeatome analysis across members of the Tytonidae, including other two species, the Western barn owl (Tyto alba), and the Oriental bay owl (Phodilus badius). The karyotype of T. furcata showed a 2n = 92, closely resembling that previously described for T. alba, indicating a high degree of chromosomal conservation within Tytonidae. Although T. furcata and T. alba exhibit similar karyotypic organization, comparative repeatomic analyses revealed differences in their composition, including variation in satellite DNA (satDNA) repertoires and abundance. Eight satDNA families were identified in T. furcata, nine in T. alba, and 28 in P. badius, highlighting the dynamic evolution of repetitive sequences. Several satDNA families were shared between T. furcata and T. alba, whereas some appeared species-specific, supporting the library hypothesis of satDNA evolution. In P. badius, multiple satDNAs exhibited similarity to transposable elements, suggesting that mobile elements contributed to their diversification. Cytogenetic analyses demonstrated centromeric heterochromatin distribution in T. furcata, as well as a large heterochromatic W chromosome enriched in DNA repeats. The localization of satDNAs in centromeric regions and the apparent accumulation of repeats on the W chromosome reinforce the role of repetitive sequences in chromosome organization and sex chromosome differentiation. Together, these findings reveal repeatome diversification despite conserved macrochromosomal structure and provide new insights into genome evolution and chromosomal dynamics in birds.

Animals↗