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Paper 4
Published in Amanda Rabone, Benedict Thomson, Nicky Dineen, Vincent Helyar, Aidan Shaw, The Final FRCR, 2020
Amanda Rabone, Benedict Thomson, Nicky Dineen, Vincent Helyar, Aidan Shaw
Monosomy X is Turner syndrome. Chest radiograph may demonstrate thinning of the lateral aspect of the clavicles as well thinned and narrow ribs with pseudo notching. Triploidy is the third commonest fatal chromosomal anomaly, with most associated with spontaneous abortions. Trisomy 13 is Patau syndrome. Most infants do not live more than a few days. Trisomy 18 is Edwards syndrome. The mean infant survival in this condition is 48 days.
Radiation-Induced Genetic Damage
Published in Kedar N. Prasad, Handbook of RADIOBIOLOGY, 2020
The nondisjunction of a chromosome may produce trisomy and monosomy.2 Monosomy is generally lethal at a very early embryonic stage. However, when sex chromosomes are involved, X-chromosome monosomy (X/O) leads to Turner’s syndrome, characterized by amenorrhea and various morphological abnormalities.2 Monosomy can be produced by mechanisms other than nondisjunction of the chromosome; therefore, there is no correlation between the frequency of monosomy and trisomy. Trisomies in humans are produced when sex chromosomes as well as a number of autosomal chromosomes are affected.2 Trisomies may result in early death or may cause Down’s syndrome, afflicting the bearer throughout life.
Mosaicism Mechanisms in Preimplantation Embryos
Published in Darren K. Griffin, Gary L. Harton, Preimplantation Genetic Testing, 2020
Maurizio Poli, Antonio Capalbo
Monosomies of autosomal chromosomes are usually considered as having a less negative consequence, as they are not compatible with fetal life. This means that if a mosaic embryo carrying a monosomy were transferred, in the worst-case scenario it would fail to implant or lead to early miscarriage. On the other hand, the transfer of a mosaic embryo carrying a trisomy could also potentially result in the birth of a child with a severe chromosomal aberration. Hence, because of the lack of long-term negative consequences and potential impact on the mother's and family's well-being, the transfer of an embryo showing a mosaic profile involving an autosomic monosomy can be considered “safer” than an embryo showing a mosaic autosomic trisomy. However, it is also important to note that, if a monosomy is detected, there is a considerable chance that the reciprocal trisomic cell line may be present should the TE be rebiopsied in a different location. Thus, monosomic mosaic findings for chromosomes with important fetal involvement (listed previously), should be considered at the same risk level of trisomic mosaic ones. For all the other potentially mosaic configurations, morphological grading should be used to prioritize embryos without altered CNVs, as the use of mosaicism criteria is currently not supported by sufficient clinical evidence.
Genetic variations as molecular diagnostic factors for idiopathic male infertility: current knowledge and future perspectives
Published in Expert Review of Molecular Diagnostics, 2021
Mohammad Karimian, Leila Parvaresh, Mohaddeseh Behjati
Chromosomal aberrations, both numerical and structural in nature, can have profound effects on fertility. The frequency of chromosomal abnormalities in the general population is approximately 0.6%. Most often, chromosomal aneuploidy is catastrophic for development and has been reported in all chromosomes of cases with spontaneous abortion. It is obvious that chromosomal loss (monosomy) is much more harmful than its gain (trisomy). In short, it can be the result of a non-disjunction event in gametes, precocious separation of chromatids, or a post-zygotic mitotic non-disjunction event in the embryo. Maternal age is the highest risk factor for aneuploidy [166]. It is known that all men have an aneuploid sperm ratio in their ejaculation. Aneuploid sperm level in fertile men is reported to be around 3–5%. Almost all studies on infertile men have demonstrated a significant enhancement in sperm aneuploidy level compared to their fertile counterparts [167–169]. The vast majority of studies revealed that the rate of sperm aneuploidy in infertile men has been tripled. Increased sperm aneuploidy has been reported for all infertility phenotypes including oligozoospermia, asthenozoospermia, and teratozoospermia [170].
Ring chromosome 7 in a child with T-cell acute lymphoblastic leukemia with myeloid markers
Published in Baylor University Medical Center Proceedings, 2021
Carlos A. Tirado, Andrew Reyes, Wilson Yeh, Justin Yee, Joy King, Javier Kane, William Koss
RCs are uncommon in hematological diseases.5,6 Because they often develop from double-stranded breaks occurring in each chromosomal arm followed by the subsequent fusion of their proximal ends, ring abnormalities often co-occur with deletions of the associated chromosome, as seen in the present case.6 The Mitelman Database of Chromosome Aberrations and Gene Fusions in Cancer reported 1864 cases of T-ALL, of which 16 involved RC formation (Table 1).7–16 Of these 16, five involved r(7) and the majority occurred in the context of a complex karyotype. The significance of RCs in T-ALL is unclear due to their rarity. As such, it is possible that the clinical course may be best inferred from their associated deletions. Deletions of chromosome 7p and 7q are rare in pediatric T-ALL and occur in only ∼4% of all cases.17,18 Patients with monosomy 7 or del(7p) are expected to have poorer clinical outcomes.18
Reducing misdiagnosis caused by maternal cell contamination in genetic testing for early pregnancy loss
Published in Systems Biology in Reproductive Medicine, 2020
Ludmila Volozonoka, Linda Gailite, Dmitrijs Perminov, Liene Kornejeva, Violeta Fodina, Inga Kempa, Anna Miskova
All POC samples (n = 86) were subjected to aCGH analysis irrespective of biological material quality and MCC testing. In total, 34 samples corresponded to normal female karyotype and 16 to normal male karyotype (sex ratio 2.1:1). The remaining 36 (41.9%) samples exhibited some kind of chromosomal abnormality, out of those 12 contained an XX sex chromosome set, 11 contained XY (sex ratio 1:0.9), and 13 were associated with sex chromosome copy number variations (Table 1). The majority of chromosomal imbalances were autosomal trisomies, followed by pure monosomy X (four cases). Of seven cases showing some kind of sex chromosome discrepancy, four indicated a mosaic form of X monosomy – arrmos(X)x1, while three cases were unable to be resolved using aCGH analysis alone. Lastly, following structural aberrations were detected: loss of 8p23.2p11.21, gain of 22q13.2q13.33, and combined gain of 11p15.5p15.2 and 15q26.1q26.3 in one sample.