Primary lung chordoma: a case report.

BACKGROUND: Chordoma, a rare malignant tumor arising from notochordal tissue, usually occurs along the spinal axis. Only a few published reports of primary lung chordomas exist. Herein, we present a case of primary lung chordoma and discuss important considerations for diagnosing rare chordomas. CASE PRESENTATION: We report a case of primary lung chordoma in a 39-year-old male with a history of testicular mixed germ-cell tumor of yolk sac and teratoma. Computed tomography revealed slow-growing solid lesions in the left lower lobe. We performed wedge resection for suspected germ-cell tumor lung metastasis. Histologically, large round or oval cells with eosinophilic cytoplasm were surrounded by large cells with granular, lightly eosinophilic cytoplasm. Tumor cells were physaliphorous. Immunohistochemistry was positive for brachyury, S-100 protein, epithelial membrane antigen, vimentin, and cytokeratin AE1/AE3, suggesting pulmonary chordoma. Re-examination of the testicular mixed germ-cell tumor revealed no notochordal elements. Although some areas were positive for brachyury staining, hematoxylin and eosin (HE) staining did not show morphological features typical of chordoma. Complementary fluorescence in situ hybridization (FISH) of the lung tumor confirmed the absence of isochromosome 12p and 12p amplification. Thus, a final diagnosis of primary lung chordoma was established. CONCLUSIONS: In patients with a history of testicular mixed germ cell tumors, comparison of histomorphology using HE and Brachyury staining of lung and testicular tumors, and analyzing isochromosome 12p and 12p amplification in lung tumors using FISH is pivotal for the diagnosis of rare lung chordomas.

Turner syndrome with isochromosome Xq as a cause of granulomatous hepatitis: a case report.

Introduction: Turner syndrome (TS) is the most common sex chromosome abnormality in women, caused by a complete or partial absence of the second sex chromosome. The karyotype 46, X,i(Xq) is the underlying cause in about 10% of the cases of TS. Hepatic abnormalities are frequent in TS. Granulomas are relatively common in liver samples but are very rarely reported in TS. Case presentation: A 15-year-old female with TS attended a consultation for evaluation of elevated liver enzymes. Her chromosomal analysis showed mosaicism 46, X (iso xq)100%. There were no stigmata of chronic liver disease. A liver biopsy showed granulomatous hepatitis. Other causes of hepatic granulomas have been excluded. Ursodeoxycholic acid (UDCA) therapy leads to the normalization of transaminases. Clinical discussion: Although Hepatic involvement is common and mostly asymptomatic in TS, the mechanism of liver injury is not well understood. The hepatic histological changes in these cases are variable and range from minimal abnormalities to nonalcoholic steatohepatitis (NASH), liver architectural changes, and biliary lesions. Hepatic granulomas are associated with a wide range of systemic disorders but are very rarely reported in tuner syndrome. Normalization of liver enzymes after treatment with UDCA was previously reported, but the importance of this approach is to be determined. Conclusion: Granulomatous hepatitis may be associated with TS and may be added to the histological patterns encountered in this disorder.

Defining the cellular origin of seminoma by transcriptional and epigenetic mapping to the normal human germline.

Aberrant male germline development can lead to the formation of seminoma, a testicular germ cell tumor. Seminomas are biologically similar to primordial germ cells (PGCs) and many bear an isochromosome 12p [i(12p)] with two additional copies of the short arm of chromosome 12. By mapping seminoma transcriptomes and open chromatin landscape onto a normal human male germline trajectory, we find that seminoma resembles premigratory/migratory PGCs; however, it exhibits enhanced germline and pluripotency programs and upregulation of genes involved in apoptosis, angiogenesis, and MAPK/ERK pathways. Using pluripotent stem cell-derived PGCs from Pallister-Killian syndrome patients mosaic for i(12p), we model seminoma and identify gene dosage effects that may contribute to transformation. As murine seminoma models do not exist, our analyses provide critical insights into genetic, cellular, and signaling programs driving seminoma transformation, and the in vitro platform developed herein permits evaluation of additional signals required for seminoma tumorigenesis.

Analysis of MicroRNA-371-373 supports that a subset of spermatocytic tumors demonstrates biologic features similar to those of GCNIS-derived germ cell tumors.

Spermatocytic tumors are rare testicular tumors occurring predominantly in older men. Most show a classical tripartite morphology (different from seminoma) and are benign. However, well-documented cases of malignant spermatocytic tumors exist. Our previous work showed that a subset of spermatocytic tumors exhibiting TP53 mutations, DNA methylation profiles closer to seminomas, and/or gains in chromosome 12p exhibited aggressive characteristics, including sarcomatoid transformation and metastatic dissemination. The microRNA-371-373 cluster is a promising biomarker which is upregulated in non-teratoma germ cell tumors with malignant behavior. In this work we analyze microRNAs-371-373 b y quantitative real-time polymerase chain reaction in 18 spermatocytic tumors representative of the whole clinical spectrum, including 6 with aggressive features (sarcomatoid transformation, metastases, or gains in chromosome 12p). The levels of microRNAs-371-373 were significantly higher in non-teratoma germ cell tumors compared to spermatocytic tumors, overall (p < 0.0001). Importantly, levels of microRNA-371-373 were higher in spermatocytic tumors with aggressive features compared to non-aggressive neoplasms. The highest levels were observed in one tumor showing isochromosome 12p. These results further support our previous findings that a subset of spermatocytic tumors are intermediate between so-called type II and type III germ cell tumors and that embryonic microRNAs play a role in aggressive behavior in spermatocytic tumors. Accordingly, this subset of tumors may behave aggressively and require close follow up. In the future, this opens an opportunity for microRNA testing in serum of spermatocytic tumor patients for risk stratification purposes.

Extragonadal germ cell tumors: A clinicopathologic study with emphasis on molecular features, clinical outcomes and associated secondary malignancies.

Extragonadal germ cell tumors (EGCTs) are rare, representing <5% of all germ cell tumors (GCTs). Whilst EGCTs share morphological and immunohistochemical features with their gonadal counterparts, they tend to be more aggressive and are frequently associated with secondary somatic malignancies. The aim of our study was to evaluate the clinical, morphological and immunohistochemical features, and to analyze tumors for chromosomal abnormalities of 12p, in addition to any novel genetic alterations, in a series of EGCTs. Seventy-seven EGCTs were included. Anterior mediastinum was the most common anatomic site, followed by central nervous system, retroperitoneum, sacroccygeal area, and neck. Whole genome SNP array identified isochromosome 12p in 26% of tumors. Additional cytogenetic abnormalities included the presence of gain of chr 21 in 37% of tumors. Somatic-type malignancies were identified in 8% of patients. Disease progression (metastasis and/or recurrence) was documented in 8 patients, most of whom died from their relapse. Three patients who died of disease had somatic-type malignancies. Mediastinal seminomas had a significantly better overall survival when compared to mediastinal non-seminomatous GCTs. Our study demonstrates that EGCTs share similar histologic features, but diverse clinical outcomes compared to their gonadal counterparts. Outcomes vary according to anatomic location and histologic subtypes. Our data corroborate that somatic-type malignancies are frequently encountered in mediastinal EGCTs and that their presence portends a poorer prognosis.

SMARCB1-Deficient Skull Base Chondrosarcoma with 12p Duplication Presenting as Somatic-Type Malignancy Arising from Metastatic Seminoma.

Somatic-type malignancy (STM) can occur infrequently within a primary or metastatic testicular germ cell tumor (TGCT) and is associated with dismal prognosis and survival. STM with chondrosarcomatous features is exceedingly rare and head and neck involvement has not been previously documented. A 39-year-old white man presented with nasal obstruction and epistaxis. Imaging disclosed a 6.9-cm expansile tumor involving the nasal cavity and skull base with intraorbital and intracranial extension. The histopathologic properties of the tumor were compatible with chondrosarcoma, grade II-III. Immunohistochemically, malignant cells were strongly and diffusely positive for S100 and epithelial markers, and showed loss of SMARCB1 expression. IDH1/2 mutations were not detected. Following whole-body PET scan, a 7.0-cm left testicular mass was discovered and diagnosed as seminoma with syncytiotrophoblastic cells, stage pT3NXM1b. Extensive retroperitoneal, mediastinal, and supraclavicular lymphadenopathy was also noticed. Histopathologic examination of the left supraclavicular lymph node revealed metastatic seminoma. By FISH, most metastatic nodal seminoma cells harbored 1 to 4 copies of isochromosome 12p, while the chondrosarcoma featured duplication of 12p. Presence of a malignant TGCT with disseminated supradiaphragmatic lymphadenopathy, the unique immunophenotypic properties of the skull-based chondrosarcoma and lack of IDH1/2 aberrations with gain of 12p strongly support the diagnosis of STM chondrosarcoma arising from metastatic TGCT. The patient did not respond to chemotherapy and succumbed three months after diagnosis. Although exceedingly uncommon, metastasis to the head and neck may occur in patients with TGCT. This case of STM chondrosarcoma demonstrated divergent immunophenotypic and molecular characteristics compared to "typical" examples of head and neck chondrosarcoma. High index of suspicion is advised regarding the diagnosis of lesions that present with otherwise typical histomorphology but unexpected immunohistochemical or molecular features.

Primary germ cell tumours of the mediastinum: A review with emphasis on diagnostic challenges.

This article will review current aspects of the histopathological, immunohistochemical and molecular analysis of primary mediastinal germ cell tumours (PMGCTs) as well as their aetiological, epidemiological, clinical and therapeutic features. PMGCTs represent an important differential diagnosis in the spectrum of mediastinal tumours, and their diagnosis is usually made on small tissue samples from core needle biopsies in combination with diagnostic imaging and serum tumour markers. As in lymphomas, a small biopsy is often the only viable tumour sample available from these patients, as they receive chemotherapy prior to eventual surgical resection. Pathologists therefore need to apply an efficient combination of immunohistochemical markers to confirm the diagnosis of a PMGCT and to exclude morphological mimics.

Rare within Rare: A Girl with Severe Haemophilia A and Turner Syndrome.

A coincidental occurrence of severe haemophilia A and Turner syndrome in a female person is extremely rare (less than 10 cases published). In such challenging cases, a multidisciplinary approach based on medicine of precision with full access to genetic and bio-molecular exploration is indispensable. The article presents an eight-year-old girl, with a family history of haemophilia, without significant disease signs (only post-dental extraction bleeding and a shorter stature). Discordantly, however, the investigations revealed a challenging condition: a genotype of 46,X,i(Xq), with an Isochromosome Xq responsible for the Turner syndrome and simultaneously, for the detrimental transformation, interfering with X chromosome inactivation, of an obligate hemophilia carrier into a severe hemophilia case-two distinct and provocative diseases.

SETD2 safeguards the genome against isochromosome formation.

Isochromosomes are mirror-imaged chromosomes with simultaneous duplication and deletion of genetic material which may contain two centromeres to create isodicentric chromosomes. Although isochromosomes commonly occur in cancer and developmental disorders and promote genome instability, mechanisms that prevent isochromosomes are not well understood. We show here that the tumor suppressor and methyltransferase SETD2 is essential to prevent these errors. Using cellular and cytogenetic approaches, we demonstrate that loss of SETD2 or its epigenetic mark, histone H3 lysine 36 trimethylation (H3K36me3), results in the formation of isochromosomes as well as isodicentric and acentric chromosomes. These defects arise during DNA replication and are likely due to faulty homologous recombination by RAD52. These data provide a mechanism for isochromosome generation and demonstrate that SETD2 and H3K36me3 are essential to prevent the formation of this common mutable chromatin structure known to initiate a cascade of genomic instability in cancer.

Turner Syndrome With Isochromosome Structural Abnormalities: A Case Report.

Turner syndrome (TS) is the most common cause of short stature and delayed puberty in females. Approximately half of the patients have the classic form with a genotype of 45,XO, one-fourth of patients have different mosaic forms, and the remaining one-fourth have structural abnormalities on the X chromosome. Among the structural abnormalities, the most common is isochromosome Xq. Females with structural variants of TS can present with delayed menarche, amenorrhea, and infertility rather than classic manifestations of TS. This study describes two rare variants of TS. One was a structural abnormality on the X chromosome, 46X,iso(Xq), and the other involves a mosaic variety of TS, including isochromosome X in the form of 45,XO/46X,iso(Xq). Both patients presented with short stature and secondary amenorrhea without classic manifestations of TS. In TS with or without mosaicism, the frequency of isochromosomes is reported to be about 15% to 18%. Owing to the absence of classical manifestations of TS, diagnosis may be delayed or missed. Therefore, females of short stature with secondary amenorrhea should be evaluated for rare variants of TS by chromosomal analysis.

Isochromosome 12p Formation Regulates Vitamin D Metabolism in Testicular Cancer.

Isochromosome 12p (iChr12p) is typical in almost all invasive testicular cancers. Increased copy number of genes on 12p is associated with the development of a clinically manifest tumor; however, the causative genes have not yet been identified. Chromosome 12 harbors many genes involved in Vitamin D metabolism. RNAseq analysis of Vitamin D receptor (VDR) genes from the TCGA cohort revealed that clustering of VDR expression signatures could differentiate between pure seminomas and non-seminomatous germ cell tumors (NSGCT). Using TCGA mRNA expression of anabolic (CYP2R1, CYP27A1 and CYP27B1) and catabolic (CYP24A1) Vitamin D enzymes, positive (PTHLH, IFNG, and TNF) and negative (FGF23) feedback regulators could also clearly distinguish between pure seminomas and NSGCT. We hypothesize that the regulation of Vitamin D metabolism might be disturbed through iChr12p formation, influencing testicular carcinogenesis via increased FGF23 and PTHLH expression. While FGF23 represses CYP27B1 and activates catabolism of active hormone, increased PTHLH secretion can lead to hypercalcemia via inactivation of VDR. In conclusion, testicular cancer is associated with extensive modifications in intratesticular Vitamin D homeostasis. Further research is needed to clarify whether Vitamin D deficiency causes the formation of iChr12p and whether Vitamin D deficiency via iChr12p genomic aberration is involved in testicular carcinogenesis.

The isochromosome 20q abnormality of pluripotent cells interrupts germ layer differentiation.

Chromosome 20 abnormalities are some of the most frequent genomic changes acquired by human pluripotent stem cell (hPSC) cultures worldwide. Yet their effects on differentiation remain largely unexplored. We investigated a recurrent abnormality also found on amniocentesis, the isochromosome 20q (iso20q), during a clinical retinal pigment epithelium differentiation. Here we show that the iso20q abnormality interrupts spontaneous embryonic lineage specification. Isogenic lines revealed that under conditions that promote the spontaneous differentiation of wild-type hPSCs, the iso20q variants fail to differentiate into primitive germ layers and to downregulate pluripotency networks, resulting in apoptosis. Instead, iso20q cells are highly biased for extra-embryonic/amnion differentiation following inhibition of DNMT3B methylation or BMP2 treatment. Finally, directed differentiation protocols can overcome the iso20q block. Our findings reveal in iso20q a chromosomal abnormality that impairs the developmental competency of hPSCs toward germ layers but not amnion, which models embryonic developmental bottlenecks in the presence of aberrations.

Isochromosome Xq and the risk of metabolic comorbidities in Turner syndrome.

BACKGROUND AND AIM: Subjects with Turner syndrome (TS) are at increased risk of metabolic disorders. The objective of this study is to evaluate the prevalence of metabolic abnormalities in TS and compare the metabolic profiles of subjects with respect to their X chromosome dosage. METHODS: Sixty-four TS subjects with a mean age of 19 ± 4.9 years were included, and the prevalence of metabolic abnormalities was assessed. Out of these, 54 age and body mass index-matched TS subjects were divided into two groups based on karyotype: 45,X and 45,X/46,XX (group I; n = 33) and 46,X,i(X)(q10) and 45,X/46,X,i(X)(q10) (group II; n = 21). They were compared for blood pressure, fasting plasma glucose, homeostasis model assessment (HOMA) of insulin resistance (IR) and ß cell function (HOMA-ß), lipid profile, and percent total body fat mass (PTBFM) to assess if an extra copy of Xq contributes to a different metabolic profile. RESULTS: The prevalence of impaired fasting glucose was 7.8%. 12% of subjects had higher systolic blood pressure (SBP), and 16% had higher diastolic blood pressure for age. 53% had a deranged lipid profile. Significant differences were noted in the two groups, with higher prevalence in group II vs. group I for SBP (p = 0.03), low-density lipoprotein cholesterol (LDL-c) (p = 0.03), and PTBFM (p = 0.02). When we applied a multiple regression analysis for these outcome variables while adjusting for potential confounders known to influence the cardiometabolic risk profile in TS, karyotype no longer remained a significant independent variable. CONCLUSION: Extra copies of Xq do not contribute to an adverse metabolic risk profile.

Pure post-pubertal yolk sac tumor of the testis: An extremely rare and aggressive entity.

CONTEXT: Pure post-pubertal yolk sac tumors (YSTs) are an extremely rare type of malignant germ cell tumor (GCT) that account for <1 % of testicular GCTs. Clinically, they are more aggressive compared to the more common pre-pubertal counterpart. The aim of this study is to analyze the clinical presentation, ancillary tests and clinical outcomes in addition to presenting a spectrum of histomorphological features, in a case series along with a literature review. DESIGN: A retrospective review of 4 cases of pure post-pubertal YST of the testis was performed. Data collected for each patient included demographics, clinical presentation, serum markers, radiology and pathologic findings, treatment, and clinical outcomes. RESULTS: All patients presented with a testicular mass with or without associated pain and elevated serum alpha-feto protein. Mean age at presentation was 36 years (range 25-68 years). Two patients presented with metastatic disease at the time of diagnosis. Histologic patterns and features are as follows: germ cell neoplasia in-situ (n = 4), reticular/microcystic, solid, glandular, papillary, endometrioid, cystic, necrosis and angiolymphatic invasion (n = 3). Fluorescent in-situ hybridization test performed on Case 2, showed presence of isochromosome 12p and next generation sequencing showed gains of 12p. Case 1, 2 and 4 showed metastatic disease on follow-up. CONCLUSIONS: Diagnosis of pure post-pubertal YST remains challenging due to the variety of morphologic patterns often present in these tumors. Extensive sampling along with use of ancillary tests is the key for diagnosis. In this study, 75 % of cases had metastatic disease at or after the diagnosis confirming the aggressive nature of this rare entity.

Gross Chromosomal Rearrangement at Centromeres.

Centromeres play essential roles in the faithful segregation of chromosomes. CENP-A, the centromere-specific histone H3 variant, and heterochromatin characterized by di- or tri-methylation of histone H3 9th lysine (H3K9) are the hallmarks of centromere chromatin. Contrary to the epigenetic marks, DNA sequences underlying the centromere region of chromosomes are not well conserved through evolution. However, centromeres consist of repetitive sequences in many eukaryotes, including animals, plants, and a subset of fungi, including fission yeast. Advances in long-read sequencing techniques have uncovered the complete sequence of human centromeres containing more than thousands of alpha satellite repeats and other types of repetitive sequences. Not only tandem but also inverted repeats are present at a centromere. DNA recombination between centromere repeats can result in gross chromosomal rearrangement (GCR), such as translocation and isochromosome formation. CENP-A chromatin and heterochromatin suppress the centromeric GCR. The key player of homologous recombination, Rad51, safeguards centromere integrity through conservative noncrossover recombination between centromere repeats. In contrast to Rad51-dependent recombination, Rad52-mediated single-strand annealing (SSA) and microhomology-mediated end-joining (MMEJ) lead to centromeric GCR. This review summarizes recent findings on the role of centromere and recombination proteins in maintaining centromere integrity and discusses how GCR occurs at centromeres.

Isochromosome Mosaic Turner Syndrome With Epilepsy and Developmental Abnormalities: A Case Report.

Turner syndrome (TS) is a genetic disorder resulting from the partial or complete absence of one X chromosome in females. This condition gives rise to a spectrum of physical and developmental characteristics. Isochromosome mosaic Turner syndrome (IMTS) is a distinct form of this disorder, characterized by genetically different cell lineages, where one or more of the lineages contain an isochromosome X consisting of either p or q arms. While IMTS is relatively common, the relationship between IMTS and epilepsy along with developmental abnormalities remains an area of further investigation. An eight-year-old female presented with a seizure lasting more than 10 minutes, subsequent bilateral hand weakness, and an abnormal gait. Neurologic evaluation revealed a 24-hour amplitude-integrated electroencephalogram (EEG) demonstrating generalized sharp and slow waves increased with hyperventilation and left-sided delta activity. Both the brain magnetic resonance imaging (MRI) and repeated EEG, conducted while the patient was sedated, showed normal results. The patient was diagnosed with generalized epilepsy with underlying left hemispheric dysfunction. Early medical history revealed acid reflux, heightened sensitivity or aversion to certain textures, swallowing difficulties, attention-deficit/hyperactivity disorder, extremity clumsiness, and a focal seizure one year prior. In the following months, the patient continued having generalized tonic-clonic seizures and developed bilateral muscle weakness in her arms and legs. This prompted genetic testing, which revealed a karyotype of 45,X,t(17;20)(q23;p13)/46,X,I(X)(q10),t(17;20)(q23;p13) consistent with IMTS and an additional chromosomal translocation. This rare case highlights the potential association between IMTS and the development of epilepsy, emphasizing the importance of a multidisciplinary approach in evaluating TS patients. There is a need for further research that explores the genetic link between TS variants and epilepsy, as well as other intellectual disorders.

SIN3-HDAC complex-associated factor, a chromatin remodelling gene located in the 12p amplicon, is a potential germ cell tumour-specific oncogene.

A genetic hallmark of malignant germ cell tumours (GCTs) is isochromosome 12p, but oncogenes located in 12p that are specifically expressed in GCT have not yet been identified. SIN3-HDAC complex-associated factor (SINHCAF) is a subunit of the Sin3/histone deacetylase (HDAC) complex, and it defines a Sin3a-Hdac complex variant that is required for the self-renewal of mouse embryonic stem cells. This study demonstrated that SINHCAF is expressed in a vast majority of malignant GCTs and is rarely expressed in somatic malignancy. Fluorescence in situ hybridisation revealed SINHCAF amplification in malignant GCTs. SINHCAF silencing using shRNA reduced anchorage-dependent cell proliferation and tumoursphere formation and inhibited tumour cell migration and invasion in GCT cell lines. Moreover, in the GCT cell line NTERA2/D1, SINHCAF silencing inhibited the expression of genes associated with embryonic stem cells and induced the expression of genes associated with neuronal and white fat cell differentiation. Compared with somatic cell lines, GCT cell lines were more susceptible to HDAC inhibitor treatment. Thus, we identified SINHCAF to be a potential oncogene located in the amplicon of chromosome 12p and showed that SINHCAF was specifically expressed in malignant GCTs. HDAC inhibitor treatment may counteract the oncogenic activity of SINHCAF and is a promising therapeutic approach for GCTs. © 2022 The Pathological Society of Great Britain and Ireland.

[Testicular tumours from a clinical point of view : What urologists and oncologists need to know from the pathologist about testicular cancer]. / Hodentumoren aus klinischer Sicht : Was Urolog:Innen und Onkolog:Innen von Patholog:Innen über Hodentumoren wissen müssen.

BACKGROUND: Testicular germ cell tumours (GCTs) are the most frequent solid malignancy in younger males aged 15-40. The differentiation between seminomas and non-seminomas impacts prognosis, clinical management and follow-up procedures. With stage- and risk-adapted multimodal treatment approaches, GCTs have an exceptionally good prognosis. Therefore, avoiding overtreatment to reduce treatment-related long-term side effects is of utmost importance. Clinical and histopathological risk factors aid in treatment decision-making. OBJECTIVES: Discussion of (histo-)pathological characteristics that directly influence treatment decision-making by urologists and oncologists. MATERIALS AND METHODS: Non-systematic literature review to describe histopathological features for interdisciplinary treatment planning. RESULTS: Key histopathological characteristics for clinicians are: (i) identification of a GCT, if necessary by 12p aberration analysis, (ii) description of the different subtypes, and (iii) risk factors, including lymphovascular invasion and/or rete testis infiltration and size of the primary tumour. Molecular pathological analyses, that is, genomic sequencing, is not part of routine diagnostics due to the lack of prognostic/predictive markers and effective targeted treatment approaches. DISCUSSION: Detailed histopathology reporting, ideally with a synoptic template, is the basis for planning and conducting guideline-endorsed, risk-adapted, multi-disciplinary management of GCTs. Along with radiographic imaging and assessment of the serum tumour markers AFP and ß­HCG (especially in non-seminomas), histopathology is crucial to maintain success and reduce the burden of GCT treatment.

Genome characterization and CRISPR-Cas9 editing of a human neocentromere.

The maintenance of genome integrity is ensured by proper chromosome inheritance during mitotic and meiotic cell divisions. The chromosomal counterpart responsible for chromosome segregation to daughter cells is the centromere, at which the spindle apparatus attaches through the kinetochore. Although all mammalian centromeres are primarily composed of megabase-long repetitive sequences, satellite-free human neocentromeres have been described. Neocentromeres and evolutionary new centromeres have revolutionized traditional knowledge about centromeres. Over the past 20 years, insights have been gained into their organization, but in spite of these advancements, the mechanisms underlying their formation and evolution are still unclear. Today, through modern and increasingly accessible genome editing and long-read sequencing techniques, research in this area is undergoing a sudden acceleration. In this article, we describe the primary sequence of a previously described human chromosome 3 neocentromere and observe its possible evolution and repair results after a chromosome breakage induced through CRISPR-Cas9 technologies. Our data represent an exciting advancement in the field of centromere/neocentromere evolution and chromosome stability.

Clinical and molecular cytogenetic findings and pregnancy outcomes of fetuses with isochromosome Y.

BACKGROUND: The mosaic forms and clinical phenotypes of fetuses with isochromosome Y are difficult to predict. Therefore, we summarized the cases of nine fetuses with isochromosome Y identified in prenatal diagnosis with a combination of molecular cytogenetic techniques, providing clinical evidence for prenatal genetic counseling. METHODS: The prenatal diagnosis and pregnancy outcomes of nine fetuses with isochromosome Y were obtained by a  retrospective analysis. Isochromosome Y was identified prenatally by different approaches, such as conventional karyotyping, chromosomal microarray analysis (CMA), quantitative fluorescent polymerase chain reaction (QF-PCR) and fluorescence in situ hybridization (FISH). RESULTS: Seven idic(Y) fetuses and two i(Y) fetuses were identified. One fetus was complete for i(Y)(p10), and the rest with 45,X had mosaic forms. A break and fusion locus was identified in Yp11.3 in one fetus, in Yq11.22 in six fetuses and in Yp10 in two fetuses. The CMA results suggested that different deletions and duplications were found on the Y chromosome. The deletion fragments ranged from 4.7 Mb to the entire Y chromosome, and the duplication fragments ranged from 10.4 to 18.0 Mb. QF-PCR analysis suggested that the AZF region was intact in one fetus, four fetuses had AZFb+c+d deletion, one fetus had AZFa+b+c+d deletion, and one fetus had AZFc+d deletion. Finally, four healthy male neonates were delivered successfully, but the parents of the remaining five fetuses, including three healthy and two unhealthy fetuses, chose to terminate their pregnancies. CONCLUSION: The fetus and neonate phenotype of prenatally detected isochromosome Y usually is that of a normally developed male, ascertained in the absence of other indicators of a fetal structural anomaly. Our study provides clinical reference materials for risk assessment and permits better prenatally counseling and preparation of parents facing the birth of isochromosome Y fetuses.