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Preimplantation Genetic Testing for Structural Rearrangements
Published in Carlos Simón, Carmen Rubio, Handbook of Genetic Diagnostic Technologies in Reproductive Medicine, 2022
Inmaculada Campos-Galindo, Vanessa Peinado
Constitutional chromosomal rearrangements can be inherited from a carrier parent or occur de novo in the gametes that result in zygotes [11]. Structural chromosomal rearrangements indicate changes in the native structure of the chromosomes. There are two general types of structural chromosomal rearrangements: balanced with no loss or gain of genetic material, and unbalanced with loss or gain of genetic material (Table 12.1). Carriers of structural chromosome rearrangements have an increased risk of fertility problems, recurrent miscarriages, and offspring with congenital abnormalities and mental retardation. Thus, preimplantation genetic testing for structural rearrangements (PGT-SR) is widely applied when an abnormal karyotype is identified in the infertility work-up of couples.
Inherited Defects in Immune Defenses Leading to Pulmonary Disease
Published in Stephen D. Litwin, Genetic Determinants of Pulmonary Disease, 2020
A group of four monogenic inherited conditions all exhibit chromosomal instability; these conditions are ataxia telangiectasia, Bloom's syndrome, Xeroderma pigmentosum, and Fanconi's syndrome. The similarities between these disorders, in addition to the observed high incidence of chromosomal rearrangement, include a high incidence of malignancy, growth problems (in some cases), and, more recently detailed, immune dysfunction. Pulmonary infections are high in this group presumably as a direct consequence of the immune impairment.
Genetic Counseling for Preimplantation Genetic Testing
Published in Darren K. Griffin, Gary L. Harton, Preimplantation Genetic Testing, 2020
Lauri D. Black, Jill M. Fischer
Another main concept to impart to the patient is that the current typical test detects unbalanced results but cannot differentiate balanced from normal results, as both have the same amount of chromosomal material present; these tests study quantity of material, not structure of the chromosomes. Overall, most patients accept this limitation given they themselves have a balanced form of the chromosomal rearrangement.
Self-reported effects of perceived social support on marital quality in balanced translocation patients and their spouses undergoing preimplantation genetic testing in China: actor–partner interdependence model
Published in Journal of Obstetrics and Gynaecology, 2022
Fengyi Mo, Xiaorui Hu, Qing Ma, Li Zhang, Lanfeng Xing
Chromosomal abnormalities, one of the most frequent causes of genetic diseases (Mierla et al. 2015), are defined as a genetic disease caused by abnormalities in the number, morphology or structure of chromosomes, often resulting in miscarriage, congenital mental retardation, mental retardation and multiple malformations (Chen et al. 2020). The most frequent chromosomal abnormalities are balanced chromosomal rearrangement, sex chromosomal mosaicism and inversion. The rate of a chromosomal anomaly in the general population is 0.37–1.86%; however, the rate in patients with a history of adverse pregnancy is 3.95–14.3% (Liu et al. 2013). Chromosomal abnormalities cannot be treated medically since they are irreversible (Chen et al. 2020). Balanced translocation is a situation in which both breakage and reconnection of chromosomes occur at abnormal positions, including both Robertsonian and reciprocal translocations. Approximately, 0.5–5% of couples with reproductive problems carry a balanced translocation (Munné et al. 2000; Findikli et al. 2003). However, at present, the specific mechanisms underlying balanced translocation remain unclear (Chen et al. 2020).
MYCN amplification levels in primary retinoblastoma tumors analyzed by Multiple Ligation-dependent Probe Amplification
Published in Ophthalmic Genetics, 2021
Elizabeth A. Price, Roopal Patel, Irene Scheimberg, Esin Kotiloglu Karaa, Mandeep S. Sagoo, M. Ashwin Reddy, Zerrin Onadim
A small set of the Rb tumors were analyzed by Whole Genome Sequencing (WGS), including 10 where one or two pathogenic variants were missing after routine screening (18). This set included two MYCNA tumors, both with late onset (over 35 months). In 9/10 cases WGS identified simple rearrangements, complex intra-chromosomal and inter-chromosomal rearrangements, and one case of potential chromothripsis. Despite the increased resolution of WGS, where the rearrangement patterns were complicated (6/10 cases) it was not possible to confirm whether both copies of RB1 were affected. Even after a complete RB1 screen and WGS, 1 of the 10 samples was left with no second pathogenic variant identified, suggesting that a minority of tumors maybe disrupted via other mechanisms. These could be epigenetic mechanisms (e.g. noncoding RNA regulation) which may be influenced by MYCN amplification.
Fetal Genetic Diagnosis by Chorionic Villus Sampling: Evaluation of the Five-Year Experience from a Single Center
Published in Fetal and Pediatric Pathology, 2021
Filiz Halici Öztürk, Fatma Doga Öcal, Seyit Ahmet Erol, Kadriye Yakut, Merve Öztürk, Yüksel Oguz, Esra Sükran Çakar, Sevki Celen, Ali Turhan Çaglar
First trimester screening is an efficacious test for determination of trisomy 21,13, and 18 [22]. Alamillo et al. showed that some screen positive fetuses have other numerical and structural chromosomal abnormalities [23]. Most of these abnormalities are clinically insignificant chromosomal rearrangements such as aneuploid mosaicism, balanced inversion or translocation, and unbalanced translocation. In this study, in regard to CVS performed for screen positivity (171 cases), trisomy 21, 13, and 18 constituted 75,8% of all detected chromosomal abnormalities (22 of 29 cases). The other detected chromosomal abnormalities were 45,X (1 case), 47,XXY (1 case), triploidy (1 case), tetraploidy (1 case), and balanced inversion (3 cases). Therefore, before performing CVS, parents should be counseled about the possible detection of different chromosomal abnormalities other than those indicated by screen tests and further evaluation might be required.