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The Host Response to Grafts and Transplantation Immunology
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
MHC antigens are inherited en bloc by offspring. As shown in Figure 11.4, each parent has a pair of homologous chromosomes, each encoding an HLA haplotype. Haplotype refers to the set of MHC genes, one from each locus, encoded on one of the homologous chromosomes. The offspring inherit one haplotype from each parent. Therefore, children inherit one of four possible combinations. The genes are closely linked on the chromosome and crossing over occurs infrequently (~1 percent). Crossing over occurs when genetic material is exchanged between chromosomes during meiosis.
Aneuploidy in Human Oocytes and Preimplantation Embryos
Published in Carlos Simón, Carmen Rubio, Handbook of Genetic Diagnostic Technologies in Reproductive Medicine, 2022
MeioMapping also revealed some unexpected features of recombination and its effect on chromosome segregation. Normally, crossing over has been considered on a per bivalent basis such that if a crossover occurred between the two homologous chromosomes, chromosome segregation would proceed with high fidelity. This was referred to as the “obligate” crossover (e.g., [100]). However, Ottolini, et al. (2015) found that what happens to individual chromatids also influences their segregation. Non-recombinant chromatids that did not engage in recombination reactions (although its sister chromatid did) are vulnerable and at increased risk of undergoing PSSC/predivision (Figure 8.9). These findings open new areas of investigation as access to oocytes and new single-cell technologies improve.
Mobile DNA Sequences and Their Possible Role in Evolution
Published in S. K. Dutta, DNA Systematics, 2019
Georgii P. Georgiev, Yurii V. Ilyin, Alexei P. Ryskov, Tatiana I. Gerasimova
In some cases, the transposon-dependent deletions can appear as a result of unequal crossing over rather than of nonprecise excision. One may suggest that if two similar transposons are located in the different but close sites on the chromosome, the unequal crossing over would occur leading to small deletions or tandem duplications. Unequal crossing over was demonstrated in the case of mdg BEL160 and for the FB-element161 inserted into the white locus, as well as in the case of Ty1 in the yeast.162 Unequal crossing over is known to play an important role in the initial stages of evolution. More frequently the excised transposon is then lost, but sometimes it may be inserted at another site on chromosomes, inducing further genome reorganization.7,35,101,148
What’s the latest with investigational drugs for soft tissue sarcoma?
Published in Expert Opinion on Investigational Drugs, 2022
Elena Cojocaru, Andrea Napolitano, Cyril Fisher, Paul Huang, Robin L Jones, Khin Thway
The phase 3 trial APROMISS compared dacarbazine vs anlotinib in patients with synovial sarcoma, randomized in a 1:2 ratio [49]. Patients had the option of crossing over on the progression of their disease and the results were presented at the ASCO meeting in 2021. A total of 79 participants received treatment with either dacarbazine or anlotinib and the PFS was statistically significant in the anlotinib arm, at 2.89 months compared to 1.64 months in the control arm with dacarbazine. Although the duration of PFS was not remarkably longer, the number of patients with a prolonged PFS was significantly higher in the anlotinib arm at 4, 6 and 12 months compared to dacarbazine (48.1%, 42.3% and 26.0% compared to 14.85%, 11.1% and 3.7%). The study has completed accrual for synovial sarcoma and leiomyosarcoma and is currently recruiting patients with alveolar soft part sarcoma. More ongoing trials are currently studying the combination of anlotinib with other active drugs in the treatment of sarcomas such as nivolumab, (NCT04165330), pegylated liposomal doxorubicin (NCT 04765228) or toripalimab (NCT04172805).
A rare Y-autosome translocation found in a patient with nonobstructive azoospermia: Case report
Published in Systems Biology in Reproductive Medicine, 2021
Anita Barišić, Alena Buretić Tomljanović, Nada Starčević Čizmarević, Saša Ostojić, Pavle Romac, Jadranka Vraneković
Furthermore, pericentric inversion 9 is the most common inversion seen in humans, with an overall frequency of approximately 1.6% (Šípek et al. 2015). Although this region is inert in nature, reproductive disorders in some carriers have been reported. This can be explained by a disruption in meiosis I that may result in unbalanced gametes (Pinho et al. 2005). Disruptions arise during crossing over from the formation of recombinant chromosomes between the normal and inverted homolog of chromosome 9 (McKinlay Gardner et al. 2018), leading to early miscarriages or live births with various anomalies. However, literature reporting on reproductive risks associated with this population variant is controversial (Merrion and Maisenbacher 2019). Regardless, when combined with the aforementioned translocation, it should be considered as an additional predisposing factor for infertility.
Genetic investigation and phylogenetic analysis of three Chinese ethnic groups using 16 X chromosome STR loci
Published in Annals of Human Biology, 2020
Ruiyang Tao, Jingyi Zhang, Ruocheng Xia, Zihao Yang, Shouyu Wang, Xiaochun Zhang, Qi Yang, Suhua Zhang, Chengtao Li
Detailed information for the 16 X-STR loci and amelogenin contained in the kit are summarised in Supplementary Table S1. Among the three ethnic groups, no statistically significant departure from HWE was observed. Furthermore, the genotyping results did not provide any evidence of LD in any pairs of the 16 X-STR loci in the Tibetan, Mongolian and Kazakh groups (Supplementary Table S2) after adjusting for multiple testing (p = .05/120), consistent with the results reported by Liu et al. in the Han population of Henan (Liu et al. 2016). That is to say, recombination and crossing-over might happen within these loci. This suggests that, in the ethnic groups from this study, allelic frequencies from these 16 X-STR loci should be adopted for forensic applications instead of haplotype frequencies.