Complex approach to the study of the Derivative Chromosome 8

Введение. Дериватная хромосома (der) - структурно аномальная хромосома, формирование которой может происходить как в результате перестроек с участием двух и более негомологичных хромосом, так и вследствие аберраций внутри одной хромосомы. Дифференциальная диагностика дериватных хромосом очень важна для выяснения происхождения хромосомной аномалии и для определения тактики медико-генетического консультирования с целью оценки повторного риска рождения ребенка с хромосомным дисбалансом. В данной работе представлены семь случаев дериватной хромосомы 8, имеющих различное происхождение и механизмы формирования, а также протокол обследования пациентов с дериватной хромосомой 8 в кариотипе. Цель: изучить структуру и механизмы формирования дериватных хромосом 8. Методы: стандартное цитогенетическое исследование, M-FISH, MCB8, FISH с локус-специфичными субтеломерными ДНК-зондами, FISH с несерийными ДНК-зондами на район р23.1 хромосомы 8. Результаты. В результате проведенного стандартного цитогенетического исследования в кариотипе семи неродственных пробандов была обнаружена дериватная хромосома 8. При использовании цитогенетического и молекулярно-цитогенетического подходов было установлено, что у четырех пациентов дериватная хромосома 8 возникла в результате инвертированной дупликации/делеции 8р, а у трех - несбалансированной транслокации с участием хромосомы 8: der(8)t(8;17), der(8)t(8;12) и der(8)t(7;8). Во всех случаях был определен механизм формирования хромосомных перестроек. Дериватные хромосомы транслокационного происхождения в двух случаях были сформированы de novo, а в одном случае - как результат патологической мейотической сегрегации отцовской реципрокной транслокации. Все дериватные хромосомы с инвертированной дупликацией/делецией 8р были следствием эктопической рекомбинации. Заключение. Представленные результаты демонстрируют целесообразность комплексного лабораторного подхода в изучении структуры и происхождения дериватной хромосомы 8. Характеристика происхождения хромосомного дисбаланса является неотъемлемой частью обследования пациентов со структурно аномальной хромосомой 8 в кариотипе. Background. Derivative chromosome (der) is a structurally abnormal chromosome, the formation of which can occur as a result of rearrangements with the participation of two or more non-homologous chromosomes, or be the result of aberrations within one chromosome. Differential diagnosis of derivative chromosomes is very important for clarifying the origin of the chromosomal abnormality and for determining the tactics of medical genetic counseling in order to assess the repeated risk of chromosomal imbalance. This work presents seven cases of a derivative chromosome with different origins and mechanisms of formation, as well as a protocol for examining patients with derivative chromosome 8 in the karyotype. Aim: to study the structure and mechanisms of formation of the derivative chromosome 8. Methods. GTG-banded chromosomal analysis, M-FISH, MCB8, FISH with subtelomeric DNA probes, FISH with home-made DNA probes for 8p23.1. Results. As a result of a conventional cytogenetic study of seven unrelated probands a derivative chromosome 8 was found. In all cases, the mechanism of the formation of chromosomal rearrangements was determined. Derivative chromosomes of translocation origin were formed de novo in two cases- der(8)t(8;12) and der(8)t(7;8), and in one case -der(8)t(8;17) - as a result of malsegregation of the paternal reciprocal translocation. In the remaining four cases, the derivative chromosomes were identified as an inverted duplication/deletion 8p due to ectopic recombination. Conclusion. The presented results demonstrate the feasibility of an integrated laboratory approach in the diagnosis of derivative chromosome 8. Characterization of the origin of chromosomal imbalance is an integral part of the examination of patients with structurally abnormal chromosome 8 in the karyotype.

Chromosome 10 abnormality predicts prognosis of neuroblastoma patients with bone marrow metastasis

Background Neuroblastoma (NB) is the most common extracranial solid tumor in children. It is known for high heterogeneity and concealed onset. In recent years, the mechanism of its occurrence and development has been gradually revealed. The purpose of this study is to summarize the clinical characteristics of children with NB and abnormal chromosome 10, and to investigate the relationship between the number and structure of chromosome 10 abnormalities and NB prognosis. Methods Chromosome G-banding was used at the time of diagnosis to evaluate the genetics of chromosomes in patients with NB and track their clinical characteristics and prognosis. All participants were diagnosed with NB in the Medical Oncology Department of the Beijing Children’s Hospital from May 2015 to December 2018 and were followed up with for at least 1 year. Results Of all 150 patients with bone marrow metastases, 42 were clearly diagnosed with chromosomal abnormalities. Thirteen patients showed abnormalities in chromosome 10, and chromosome 10 was the most commonly missing chromosome. These 13 patients had higher LDH and lower OS and EFS than children with chromosomal abnormalities who did not have an abnormality in chromosome 10. Eight patients had both MYCN amplification and 1p36 deletion. Two patients had optic nerve damage and no vision, and one patient had left supraorbital metastases 5 months after treatment. Conclusions The results indicated that chromosome 10 might be a new prognostic marker for NB. MYCN amplification and 1p36 deletion may be related to chromosome 10 abnormalities in NB. Additionally, NB patients with abnormal chromosome 10 were prone to orbital metastases.

Chromosome 10 Abnormality Predicts Prognosis of Neuroblastoma Patients With Bone Marrow Metastasischromosome 10 Abnormality Predicts Prognosis of Neuroblastoma Patients With Bone Marrow Metastasis

Background Neuroblastoma (NB) is the most common extracranial solid tumor in children with high heterogeneity and concealed onset. The mechanism for its occurrence and development has not been revealed. The purpose of this study was to summarize the clinical characteristics of children with NB and abnormal chromosome 10. To investigate the relationship between the number and structure of chromosome 10 abnormality and NB prognosis.MethodsWe used chromosome G-banding in the first diagnosis to evaluate the genetics of chromosomes in patients with NB, and follow up their clinical characteristics and prognosis. All participants were diagnosed with NB in Hematology Oncology Center, Beijing Children’s Hospital from May 2015 to December 2018, and were followed up for at least one year. ResultsOf all 150 patients with bone marrow metastases, 42 were clearly diagnosed with chromosomal abnormalities. There were 13 patients with chromosome 10 abnormalities definitely, and the loss of chromosome 10 was the most common decrease in the number of chromosomes. These 13 patient had higher LDH, lower OS and EFS than that of children in abnormal group without chromosome 10 abnormality. Eight patients both had MYCN amplification and 1p36 deletion. Two of them had optic nerve damage and no vision, and 1 had left supraorbital metastases five months after treatment. Among the 16 children with suspected chromosome 10 abnormalities, 3 also had orbital metastases. ConclusionsThe above results showed that chromosome 10 might be a new prognostic marker. MYCN amplification and 1p36 deletion may be related with chromosome 10 abnormalities in NB. And NB patients with abnormal chromosome 10 were prone to have orbital metastases.

Nuclear Isoforms of Neurofibromin Are Required for Proper Spindle Organization and Chromosome Segregation

Mitotic spindles are highly organized, microtubule (MT)-based, transient structures that serve the fundamental function of unerring chromosome segregation during cell division and thus of genomic stability during tissue morphogenesis and homeostasis. Hence, a multitude of MT-associated proteins (MAPs) regulates the dynamic assembly of MTs in preparation for mitosis. Some tumor suppressors, normally functioning to prevent tumor development, have now emerged as significant MAPs. Among those, neurofibromin, the product of the Neurofibromatosis-1 gene (NF1), a major Ras GTPase activating protein (RasGAP) in neural cells, controls also the critical function of chromosome congression in astrocytic cellular contexts. Cell type- and development-regulated splicings may lead to the inclusion or exclusion of NF1exon51, which bears a nuclear localization sequence (NLS) for nuclear import at G2; yet the functions of the produced NLS and ΔNLS neurofibromin isoforms have not been previously addressed. By using a lentiviral shRNA system, we have generated glioblastoma SF268 cell lines with conditional knockdown of NLS or ΔNLS transcripts. In dissecting the roles of NLS or ΔNLS neurofibromins, we found that NLS-neurofibromin knockdown led to increased density of cytosolic MTs but loss of MT intersections, anastral spindles featuring large hollows and abnormal chromosome positioning, and finally abnormal chromosome segregation and increased micronuclei frequency. Therefore, we propose that NLS neurofibromin isoforms exert prominent mitotic functions.

Application of Copy Number Variation Sequencing in Genetic Analysis of Miscarriages in Early and Middle Pregnancy

High-throughput sequencing based on copy number variation (CNV-seq) is commonly used to detect chromosomal abnormalities. This study identifies chromosomal abnormalities in aborted embryos/fetuses in early and middle pregnancy and explores the application value of CNV-seq in determining the causes of pregnancy termination. High-throughput sequencing was used to detect chromosome copy number variations (CNVs) in 116 aborted embryos in early and middle pregnancy. The detection data were compared with the Database of Genomic Variants (DGV), the Database of Chromosomal Imbalance and Phenotype in Humans using Ensemble Resources (DECIPHER), and the Online Mendelian Inheritance in Man (OMIM) database to determine the CNV type and the clinical significance. High-throughput sequencing results were successfully obtained in 109 out of 116 specimens, with a detection success rate of 93.97%. In brief, there were 64 cases with abnormal chromosome numbers and 23 cases with CNVs, in which 10 were pathogenic mutations and 13 were variants of uncertain significance. An abnormal chromosome number is the most important reason for embryo termination in early and middle pregnancy, followed by pathogenic chromosome CNVs. CNV-seq can quickly and accurately detect chromosome abnormalities and identify microdeletion and microduplication CNVs that cannot be detected by conventional chromosome analysis, which is convenient and efficient for genetic etiology diagnosis in miscarriage.

Preimplantation Genetic Testing of Aneuploidy by Next Generation Sequencing: Association of Maternal Age and Chromosomal Abnormalities of Blastocyst

BACKGROUND: Aneuploidy is a major cause of miscarriages and implantation failure. Preimplantation genetic testing for aneuploidy (PGT-A) by Next Generation Sequencing (NGS) is able to detect of the numeral and structural chromosomal abnormalities of embryos in vitro fertilization (IVF). AIM: This study was aimed to assess the relationship between maternal age and chromosomal abnormalities NGS technology. METHODS: 603 human trophectoderm (TE) biopsied samples were tested by Veriseq kit of Illumina. The relation of marternal age and chromosomal abnormality of blastocyst embryo was evaluated. RESULTS: Among the 603 TE samples, 247 samples (42.73%) presented as chromosomal abnormalities. The abnormalities occurred to almost chromosomes, and the most popular aneuploidy observed is 22. Aneuploidy rate from 0.87% in chromosome 11 to 6.06% in chromosome 22. The rate of abnormal chromosome increased dramatically in group of mother's ages over 37 (54.17%) comparing to group of mother's ages less than 37 (38.05%) (p < 0.000). The Abnormal chromosome and maternal age has a positive correlation with r = 0.4783 (p<0.0001). CONCLUSION: These results showed high rate abnormal chromosome and correlated with advanced maternal age of blastocyst embryos.