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.

Primary mediastinal germ cell tumor and clonally related and unique hematologic neoplasms with i(12p) and TP53 mutation: A report of two cases.

The development of clonally related hematologic neoplasms in the setting of primary mediastinal germ cell tumors (PMGCTs) has been recognized previously and is associated with a dismal prognosis. However, the presentation of hematologic neoplasms as chronic myelomonocytic leukemia (CMML) and hemophagocytic lymphohistiocytosis (HLH) has been rarely reported. Here we report two patients with PMGCTs and hematologic neoplasms. The PMGCT was composed mostly of yolk sac tumor whereas the hematologic neoplasms had morphologic features that resembled CMML and HLH. The hematologic neoplasms from both patients harbored isochromosome 12p [i(12p)] and TP53 mutations, supporting a clonal relationship between these tumors. This association represents a unique clinical syndrome that likely contributes to the poor clinical outcome of these patients.

Prenatal Diagnosis of Placental Mesenchymal Dysplasia with 46, X, Isochromosome Xq/45, X Mosaicism.

Placental mesenchymal dysplasia is an uncommon vascular anomaly of the placenta with characteristics of placentomegaly and multicystic appearance and with or without association with fetal chromosomal anomaly. We present a unique placental mesenchymal dysplasia patient with amniotic fluid karyotyping as 46, X, iso(X) (q10). Detailed molecular testing of the amniotic fluid, fetal cord blood, non-dysplastic placenta and dysplastic placenta was conducted after termination of pregnancy, from which we proved biparental/androgenetic (46, X, i(X) (q10)/45, X) mosaicism in different gestational tissues. A high portion of androgenetic cells in dysplastic placenta (74.2%) and near 100% of biparental cells in the fetus's blood and amniotic fluid were revealed. Delicate mosaic analyses were performed, and possible pathogenesis and embryogenesis of this case were drawn up.

Prenatal diagnosis of de novo isochromosome 4p with an unbalanced t(4;9) translocation in a fetus with congenital anomalies: A case report and literature review.

OBJECTIVE: We present the first case of prenatally diagnosed isochromosome 4p with whole 4q arm translocating to chromosome 9p23 and review the literature. CASE REPORT: A 26-year-old woman underwent amniocentesis at 25 weeks of gestation because of an abnormal ultrasound examination. Routine chromosome analysis on cultured amniocytes showed a karyotype of 46,XX, ?idic(4)(q11),der(9)t(4;9)(q11;p23). Single nucleotide polymorphism (SNP) array analysis on uncultured amniocytes detected two copy number variations (CNVs): arr [GRCh37] 4p16.3p11(68345-49089361) × 3; arr [GRCh37] 9p24.3p23(208454-10039391) × 1. The karyotypes of the parents were normal, indicating that the chromosomal rearrangement was de novo. According to the fetal-parent trios SNP analysis, both the abnormal chromosomes were originated from the father. The pregnancy was terminated at 30 weeks of gestation, and a malformed fetus was delivered with dysmorphic craniofacial, short neck, wide-spaced nipples and rocker-bottom feet. CONCLUSION: The combined application of traditional cytogenetic technology and molecular diagnosis technology in prenatal diagnosis helps identify genetic components and the origin of isochromosome, which enable clinicians to precisely predict the fetal prognosis and provide accurate genetic counselling and fertility guidance.

Whole-chromosome arm acquired uniparental disomy in cancer development is a consequence of isochromosome formation.

Using SNP-based microarray data from The Cancer Genome Atlas (TCGA), we investigated isochromosomes (deletion of one arm and duplication of the other arm) and related acquired uniparental disomy in 12 tumor types. We observed a high frequency of isochromosomes (25.98%) across all type of tumors except thyroid cancers. The highest frequency of isochromosomes was found in lung squamous cell carcinoma (54.18%). Moreover, whole-chromosome arm acquired uniparental disomy (aUPD) was common in the deleted arms of isochromosomes. These data are consistent with whole-chromosome arm aUPD likely being a consequence of isochromosomes formation. Our findings implicated aUPD as occurring through error-prone DNA repair of a deleted arm or segment of a chromosome that leads to homozygosity for existing alterations. Isochromosomes were significantly more frequent in TP53 mutated samples than wild types in 6 types of tumors with loss of TP53 function potentially contributing to development of isochromosomes. Isochromosomes are common alterations in cancer, and losing one arm of a chromosome could result in duplication of the lost arm. Duplication of the remaining arm leads promulgation of the effects on any defects in the remaining allele, due to subsequent homozygosity.

Myelodysplastic/myeloproliferative neoplasms-unclassifiable with isolated isochromosome 17q represents a distinct clinico-biologic subset: a multi-institutional collaborative study from the Bone Marrow Pathology Group.

Classification of myeloid neoplasms with isolated isochromosome i(17q) [17p deletion with inherent monoallelic TP53 loss plus 17q duplication] is controversial. Most cases fall within the WHO unclassifiable myelodysplastic/myeloproliferative neoplasms (MDS/MPN-U) category. The uniformly dismal outcomes warrant better understanding of this entity. We undertook a multi-institutional retrospective study of 92 adult MDS/MPN-U cases from eight institutions. Twenty-nine (32%) patients had isolated i(17q) [MDS/MPN-i(17q)]. Compared to MDS/MPN without i(17q), MDS/MPN-i(17q) patients were significantly younger, had lower platelet and absolute neutrophil counts, and higher frequency of splenomegaly and circulating blasts. MDS/MPN-i(17q) cases showed frequent bilobed neutrophils (75% vs. 23%; P = 0.03), hypolobated megakaryocytes (62% vs. 20%; P = 0.06), and a higher frequency of SETBP1 (69% vs. 5%; P = 0.002) and SRSF2 (63% vs. 5%; P = 0.006) mutations that were frequently co-existent (44% vs. 0%; P = 0.01). TP53 mutations were rare. The mutation profile of MDS/MPN-U-i(17q) was similar to other myeloid neoplasms with i(17q) including atypical chronic myeloid leukemia, chronic myelomonocytic leukemia, myelodysplastic/myeloproliferative neoplasm with ring sideroblasts and thrombocytosis, myelodysplastic syndrome and acute myeloid leukemia, with frequent concomitant SETBP1/SRSF2 mutations observed across all the diagnostic entities. Over a median follow-up of 52 months, patients with MDS/MPN-i(17q) showed a shorter median overall survival (11 vs. 28 months; P < 0.001). The presence of i(17q) retained independent poor prognostic value in multivariable Cox-regression analysis [HR 3.686 (1.17-11.6); P = 0.026] along with splenomegaly. We suggest that MDS/MPN-i(17q) warrants recognition as a distinct subtype within the MDS/MPN-U category based on its unique clinico-biologic features and uniformly poor prognosis.

Molecular Cytogenetic Classification of Down Syndrome and Screening of Somatic Aneuploidy in Mothers.

Down Syndrome (DS) caused by trisomy 21 results in various congenital and developmental complications in children. It is crucial to cytogenetically diagnose the DS cases early for their proper health management and to reduce the risk of further DS childbirths in mothers. In this study, we performed a cytogenetic analysis of 436 suspected DS cases using karyotyping and fluorescent in situ hybridization. We detected free trisomies (95.3%), robertsonian translocations (2.4%), isochromosomes (0.6%), and mosaics (1.2%). We observed a slightly higher incidence of DS childbirth in younger mothers compared to mothers with advanced age. We compared the somatic aneuploidy in peripheral blood of mothers having DS children (MDS) and control mothers (CM) to identify biomarkers for predicting the risk for DS childbirths. No significant difference was observed. After induced demethylation in peripheral blood cells, we did not observe a significant difference in the frequency of aneuploidy between MDS and CM. In conclusion, free trisomy 21 is the most common type of chromosomal abnormality in DS. A small number of DS cases have translocations and mosaicism of chromosome 21. Additionally, somatic aneuploidy in the peripheral blood from the mother is not an effective marker to predict DS childbirths.

The genomic landscape of teenage and young adult T-cell acute lymphoblastic leukemia.

BACKGROUND: Treatment on risk adapted intensive pediatric protocols has improved outcome for teenagers and young adults (TYA) with T-cell acute lymphoblastic leukemia (T-ALL). Understanding the biology of disease in this age group and the genetic basis of relapse is a key goal as patients with relapsed/refractory disease have poor outcomes with conventional chemotherapy and novel molecular targets are required. This study examines the question of whether TYA T-ALL has a specific biological-molecular profile distinct from pediatric or adult T-ALL. METHODS: Genomic characterization was undertaken of a retrospective discovery cohort of 80 patients aged 15-26 years with primary or relapsed T-ALL, using a combination of Genome-Wide Human SNP Array 6.0, targeted gene mutation and promoter methylation analyses. Findings were confirmed by MLPA, real-time quantitative PCR, and FISH. Whole Exome Sequencing was performed in 4 patients with matched presentation and relapse to model clonal evolution. A prevalence analysis was performed on a final data set of 1,792 individual cases to identify genetic lesions with age specific frequency patterns, including 972 pediatric (1-14 years), 439 TYA (15-24 years) and 381 adult (≥25 years) cases. These cases were extracted from 19 publications with comparable genomic data identified through a PubMed search. RESULTS: Genomic characterization of this large cohort of TYA T-ALL patients identified recurrent isochromosome 7q i(7q) in our discovery cohort (n = 3). Prevalence analysis did not identify any age specific genetic abnormalities. Genomic analysis of 6 pairs of matched presentation - relapsed T-ALL established that all relapses were clonally related to the initial leukemia. Whole exome sequencing analysis revealed recurrent, targetable, mutations disrupting NOTCH, PI3K/AKT/mTOR, FLT3, NRAS as well as drug metabolism pathways. CONCLUSIONS: All genetic aberrations in TYA T-ALL occurred with an incidence similar or intermediate to that reported in the pediatric and adult literature, demonstrating that overall TYA T-ALL exhibits a transitional genomic profile. Analysis of matched presentation - relapse supported the hypothesis that relapse is driven by the Darwinian evolution of sub-clones associated with drug resistance (NT5C2 and TP53 mutations) and re-iterative mutation of known key T-ALL drivers, including NOTCH1.

Silencing of Transposable Elements Mediated by 5-mC and Compensation of the Heterochromatin Content by Presence of B Chromosomes in Astyanax scabripinnis.

The way in which transcriptional activity overcomes the physical DNA structure and gene regulation mechanisms involves complex processes that are not yet fully understood. Modifications in the cytosine-guanine sequence of DNA by 5-mC are preferentially located in heterochromatic regions and are related to gene silencing. Herein, we investigate evidence of epigenetic regulation related to the B chromosome model and transposable elements in A. scabripinnis. Indirect immunofluorescence using anti-5-mC to mark methylated regions was employed along with quantitative ELISA to determine the total genomic DNA methylation level. 5-mC signals were dispersed in the chromosomes of both females and males, with preferential accumulation in the B chromosome. In addition to the heterochromatic methylated regions, our results suggest that methylation is associated with transposable elements (LINE and Tc1-Mariner). Heterochromatin content was measured based on the C-band length in relation to the size of chromosome 1. The B chromosome in A. scabripinnis comprises heterochromatin located in the pericentromeric region of both arms of this isochromosome. In this context, individuals with B chromosomes should have an increased heterochromatin content when compared to individuals that do not. Although, both heterochromatin content and genome methylation showed no significant differences between sexes or in relation to the occurrence of B chromosomes. Our evidence suggests that the B chromosome can have a compensation effect on the heterochromatin content and that methylation possibly operates to silence TEs in A. scabripinnis. This represents a sui generis compensation and gene activity buffering mechanism.

Isochromosome 11q is Associated with Unique Characteristics and Poor Prognosis in Patients with Acute Myeloid Leukemia.

BACKGROUND: Isochromosome 11q in patients with acute myeloid leukemia is rarely reported, and little is known about its main features. METHODS: The presence of isochromosome 11q was identified in four patients (three adults and one child) from screening 441 patients with an acute myeloid leukemia diagnosis between 2009 and 2018 by using R-banding and fluorescence in situ hybridization. RESULTS: The child, patient 1 with unreported isochromosome (partial 11q isochromosome), accompanied with t(1;11) translocation, initially achieved remission after receiving chemotherapy. However, 4 months later this patient experienced a relapse. While multiple treatments were tried, it had no effect and the patient survived for 16 months. The remaining patients with isochromosome 11q exhibited numerical/structural chromosomal abnormal-ities involving myelodysplastic syndrome-related chromosomes 5, 7, 8, and 20. In patients 2 and 3, we found a derivative chromosome 21. Patient 3 was newly diagnosed with acute myeloid leukemia and was treated with many chemotherapy protocols, unfortunately with no effect. The patient then received traditional Chinese medicine and survived for 10 months, although she still has not achieved complete remission. Patients 2 and 4 received chemotherapy but experienced rapid disease progression and died within 2 months. CONCLUSIONS: In summary, patients with isochromosome 11q/partial 11q isochromosome have a poorer prognosis, especially for isochromosome 11q. Furthermore, these chromosome aberrations may be risk factors for the presence of isochromosome 11q or myelodysplastic syndrome-related genes, both of them may be associated with a failure to respond to treatment and poor outcomes. Hence, these discoveries may lay a foundation to study mechanisms and explore treatments.

Assessment of isochromosome 12p and 12p abnormalities in germ cell tumors using fluorescence in situ hybridization, single-nucleotide polymorphism arrays, and next-generation sequencing/mate-pair sequencing.

The identification of isochromosome 12p [i(12p)] and 12p gains have significant clinical utility in the diagnosis of germ cell tumors (GCTs). We have summarized the results of fluorescence in situ hybridization (FISH) assays to identify i(12p), performed in a Clinical Laboratory Improvement Amendments (CLIA)-validated setting for 536 specimens. In addition, the American Association for Cancer Research (AACR) Project GENIE registry and The Cancer Genome Atlas (TCGA) data sets were evaluated for chromosome 12p gains, and a limited number of cases were concurrently evaluated using FISH, single-nucleotide polymorphism (SNP) arrays and next-generation sequencing (NGS; including mate-pair sequencing). Specimens submitted for FISH testing were frequently from potential sites of metastases (male: 70.9% and female: 69.3%), and polysomy of chromosome 12 with or without concurrent i(12p) was a frequent finding, seen in 3% (16/536) and 35% (186/536) of cases, respectively. Our analysis suggests that 12p gains are likely to be present in approximately 73% of male GCT and in 32% of female GCT (AACR GENIE, n = 555). When comparing TCGA cases of testicular GCT (n = 149) to combined cases of sarcoma, colorectal, prostate, and urothelial carcinoma (n = 1754), 12p gains had a sensitivity of 77.2% and specificity of 97.3% for GCT. Some advantages of FISH over SNP arrays/NGS include relatively lower cost, rapid turnaround time, the ability to analyze biopsy material with a limited number of tumor cells (50 cells), and the ability to distinguish i(12p) from polysomy. The ability to spatially restrict the analysis to cells of interest is critical, as specimens submitted for testing often have low tumor purity. Disadvantages include false negative results due to an inability to detect segmental gains due to FISH probe design. With the availability of numerous testing modalities, including FISH, SNP arrays, and NGS-based assays, a nuanced understanding of the advantages and disadvantages of each methodology, as has been presented in this study, may inform appropriate testing strategies.

An unknown chromosomal aberration in a patient with chronic lymphocytic leukemia: Extra isochromosome 4q.

The genetic characterization of chronic lymphocytic leukemia (CLL) has made significant progress over the past few years. Chromosomal abnormalities are detected in up to 80% of patients. Determination of new chromosomal disorders is important in the pathogenesis and treatment facilities. A patient was diagnosed with CLL Stage 2 on 2012 and followed since then by hematology clinic. She was 63 years old. Mature, small lymphocytes, and smudge cell was found in the patient's peripheral blood smear. Bone marrow (BM) biopsy made and hypercellularity showing infiltration of atypical cells with CD5+, CD20+, and CD23+ were determined. Hypoplasia is detected in myeloid/erythroid series, and Stage 2 reticular fibers proliferation were detected. The patient was followed up without medication. While follow-up of patient's white blood cell: 57300, hemoglobin: 5.36, and PLT: 99700 are determined in May 2014. According to the patient's flow results, CD5+, CD23+, and FMC7+ were detected. Mature, small lymphocytes and smudge cell was found in the patient's peripheral blood smear. In ultrasonography imaging, multiple laps were found in the abdomen and multiple neck lymph nodes were detected. The patient BM aspiration was performed in 2014, and hypercellularity was found to contain 54% of atypical lymphocytes in the BM. Fluorescence in situ hybridization (FISH) analysis made two times in 2014. At first, FISH analysis patient's rate of 18% in RB1/13q14.2/13qter revealed a deletion of the gene regions. Patient's FISH result was reported as normal (for RB1/13q14.2/13qter) after 5 months at second analysis. Cytogenetic analysis is made from the patient's BM at the same time. According to the results of karyotyping and FISH, 47, XX, isochromosome 4q (+i4q) is determined. According to literature, extra isochromosome 4q is reported by our case for the first time in CLL. She was diagnosed with Stage 4 CLL and FISH treatment was initiated. Our patient showed disease progression compared to previous results. Hence, we offer that this evidence can be considered regarding triggering the disease's progression or as a result of disease progression i4q was occurred.

The detection of isochromosome i(12p) in malignant germ cell tumours and tumours with somatic malignant transformation by the use of quantitative real-time polymerase chain reaction.

AIMS: Malignant germ cell tumours (GCTs) of the testis are rare neoplasms, but the most common solid malignancies in young men. World Health Organization guidelines divide GCTs into five types, for which numerous immunohistochemical markers allow exact histological subtyping in the majority of cases. In contrast, a germ cell origin is often hard to prove in metastatic GCTs that have developed so-called somatic malignant transformation. A high percentage, up to 89%, of GCTs are characterised by the appearance of isochromosome 12p [i(12p)]. Fluorescence in-situ hybridisation has been the most common diagnostic method for the detection of i(12p) so far, but has the disadvantages of being time-consuming, demanding, and not being a stand-alone method. The aim of the present study was to establish a quantitative real-time polymerase chain reaction assay as an independent method for detecting i(12p) and regional amplifications of the short arm of chromosome 12 by using DNA extracted from formalin-fixed paraffin-embedded tissue. METHODS AND RESULTS: A cut-off value to distinguish between the presence and absence of i(12p) was established in a control set consisting of 36 tumour-free samples. In a training set of 149 GCT samples, i(12p) was detectable in 133 tumours (89%), but not in 16 tumours (11%). In a test set containing 27 primary and metastatic GCTs, all 16 tumours with metastatic spread and/or somatic malignant transformation were successfully identified by the detection of i(12p). CONCLUSION: In summary, the qPCR assay presented here can help to identify, further characterise and assign a large proportion of histologically inconclusive malignancies to a GCT origin.

Low-Level Trisomy 14 Mosaicism: A Carrier of an Isochromosome 14 and a Supernumerary Marker Chromosome 14.

Trisomy 14 (T14) mosaicism is a rare chromosomal condition characterised by various clinical features, including developmental delay, growth impairment, and dysmorphism. Here, we report on a 12-year-old female referred for cytogenetic analysis due to short stature. Standard GTG-banding analysis on the patient's peripheral blood revealed mosaic Τ14 in the form of an i(14)(q10) in 3% of cells. Furthermore, a small supernumerary marker chromosome (sSMC) had been detected in the first trimester of pregnancy in chorionic villus sampling. A skin biopsy in the patient revealed the presence of a metacentric sSMC in 100% of cells. Cytogenetic and FISH studies showed that it was a de novo metacentric bisatellited sSMC derived from chromosomes 14 or 22. Oligonucleotide array-CGH using skin cells revealed no copy number variations. Studies for uniparental disomy 14 by microsatellite analysis confirmed biparental inheritance. To the best of our knowledge, this is the second report of a patient with 2 abnormal cell lines involving chromosome 14 in different tissues, one with mosaic T14 in the form of i(14)(q10) and one with an sSMC derived from chromosome 14, present in blood and skin, respectively. A rare mechanism of trisomy rescue events is proposed to explain the presence of the different cell lines in the tissues examined. This case highlights the importance of providing the cytogenetics laboratory with adequate clinical data to test for low mosaicism and analyse different tissues if necessary, thus contributing to the suitable clinical management of the patient.

Case report: a Chinese girl with dent disease 1 and turner syndrome due to a hemizygous CLCN5 gene mutation and Isochromosome (Xq).

BACKGROUND: Female Dent disease 1 patients with low-molecular-weight proteinuria (LMWP) due to CLCN5 gene mutation were rarely reported, and these cases that the people were also with Turner syndrome (TS) were even hardly documented before. CASE PRESENTATION: Here we report a 3-year and 11-month old Chinese girl with short stature who had a karyotype of 46,X,i(X)(q10) and a de novo pathogenic variant in the CLCN5 gene on the short arm of X chromosome. Laboratory examinations showed that the patient had LMWP, hypercalciuria, hypophosphatemia, delayed bone age, and genital dysplasia. CONCLUSION: The combination of i(X)(q10) and CLCN5 mutation causes the deletion of the wild-type CLCN5 allele that results in Dent-1 and TS. To the best of our knowledge, this is the first case that a female CLCN5 mutation hemizygote is diagnosed with Dent-1 and Turner syndrome due to isochromosome X. Also, our case has indicated that the prevalence of the situation may be largely underestimated because of the mild signs of females with Dent-1.

Molecular cytogenetic characterization of an isodicentric Yq and a neocentric isochromosome Yp in an azoospermic male.

Isodicentric Y chromosomes are considered one of the most common structural abnormalities of the Y chromosome. Neocentric marker chromosomes, with neocentromeres, have drawn increasing attention in recent years. The present study reported an azoospermic male with a neocentric isochromosome Yp, neo(Yp), and an isodicentric Yq, idic(Yq). The karyotype was analyzed using G­banding, chromosome microarray analysis (CMA), and fluorescence in situ hybridization (FISH) with various detection probes, including sex­determining region on the Y chromosome (SRY) and Y centromeric, applied at the same time. G­banding initially revealed the karyotype 47,X,i(Y)(q10),+mar. CMA indicated the presence of an extra Y chromosome, seemingly equivalent to 47,XYY males. FISH delineated the existence of two centromeres on the idic(Yq). For the marker chromosome, two SRY signals were detected instead of the Y­specific centromere signal, and a visual centromere was observed. This indicated the possible existence of a neocentromere in the marker chromosome, located in the connected region in Yp11.2 band. Finally, the patient's karyotype was established as 47,X,idic(Y)(p11.2), neo(Y)(pter→Yp11.2::Yp11.2→pter). The findings suggested that both idic(Yq) and neo(Yp) could be the main causes of the patient's azoospermia, despite the fact that the partial disomy of Ypter to Yp11.2 did not lead to any major malformations. The present study not only improves the understanding of karyotype/phenotype relationships between neocentric marker Y chromosomes and male infertility, but also supports the hypothesis that the combined application of molecular cytogenetic analysis could aid in reliably confirming breakpoints, origins, and the constitution of the marker chromosomes.

Diagnosis and clinical delineation of mosaic tetrasomy 5p.

OBJECTIVE: Our objective was to review the phenotypic and genetic characteristics of tetrasomy 5p from the fetal period until adulthood including prenatal diagnostic evaluations. BACKGROUND: Tetrasomy 5p is a rare chromosomal abnormality. Of the 14 reports, most document mosaic tetrasomy 5p resulting from a supernumerary marker chromosome or isochromosome. There is a wide range of phenotypic manifestations with severity related to more proximal breakpoints and the degree of mosaicism. DESIGN: We conducted a systematic review using Scopus, PubMed Central® and Ovid MEDLINE® from inception through July 1, 2018 for all articles describing tetrasomy 5p. All articles describing the syndrome of tetrasomy 5p were included. RESULTS: Of the 15 included cases, 13 exhibited mosaic tetrasomy and two had complete tetrasomy identified by amniocentesis. The most common features include seizures (8/11 live births, 73%), hypotonia (7/11 live births, 64%), developmental delay (7/9 cases that reached childhood, 78%), abnormal external ears (6/11 live births, 55%), short stature (6/11 live births, 55%), ventriculomegaly (5/11 live births, 45.5%) and congenital heart defect (6/15 cases, 40%). The clinical phenotype ranged in severity from mild with no defining characteristics to severe with seizures, developmental delay, and multiple congenital anomalies, resulting in early death. Of these 15 cases, only 6 were diagnosed prenatally by prenatal genetic testing (40%) with prenatal ultrasound identifying abnormalities in 4/6 (67%). Confined placental mosaicism (CPM) was diagnosed in six additional cases due to discordance between CVS and amniocentesis results. Four of the five live births returned for evaluation and each showed normal development. CONCLUSIONS: Fourteen out of 15 (93%) cases of tetrasomy 5p were associated with an abnormal phenotype. Once a diagnosis is made prenatally, a detailed anatomy ultrasound and fetal echocardiogram must be performed to further characterize any structural abnormalities of the fetus and potentially estimate the clinical severity. Caution should be exercised when prenatal diagnosis of mosaic tetrasomy 5p is found by chorionic villus sampling. CVS alone is insufficient to diagnose tetrasomy 5p and needs to be confirmed with amniocentesis. Our review seeks to inform clinicians on the current literature regarding tetrasomy 5p so that they may better counsel patients when this syndrome is diagnosed.

Rare case of monocentric isochromosome Y with inversion duplication of p arm in patient diagnosed with azoospermia.

A patient presenting with azoospermia was referred for genetic evaluation, and upon karyotyping, he was revealed to have two cell lines-mos46,X,ider(Y)(q10)inv(Y)(p11.3q11.1)/45,X. Further cytogenetic studies such as C banding and fluorescence in situ hybridization were performed, which revealed an inversion duplication of a segment of the Y chromosome; hence, the derivative chromosome contained two SRY genes but only one centromere. Y chromosome microdeletion studies were performed in select STS sequences of AZFa, AZFb and AZFc regions and found to be negative for microdeletions. For such a case of infertility, the couple was advised to undergo artificial reproductive techniques with the help of donor spermatozoa.