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Preimplantation Genetic Testing for Structural Rearrangements
Published in Darren K. Griffin, Gary L. Harton, Preimplantation Genetic Testing, 2020
Sometimes the deselection of carrier embryos is necessary, especially when there is a genetic risk associated with the translocation [85]. In 2011, the first clinical case of microarray-based PGT-SR being used to distinguish between carrier and normal chromosomes was reported for that reason. With the use of SNP-array platform, Treff and colleagues have successfully distinguished carrier embryos obtained from a 28-year-old patient with Alagille syndrome which was caused by an apparently balanced translocation of 46,XX,t(2;20)(q21;p12.2). This translocation caused a microdeletion on the short arm of chromosome 20, disrupting Jagged1 gene [85,144]. Then the same group reported their retrospective analysis of 126 embryos evaluated as normal/carrier in the regular PGT-SR study. After carrier diagnosis, 62 were predicted to be normal (49%), and 64 (51%) were predicted as balanced [86]. In order to distinguish normal from balanced, the only prerequisite is that it is necessary to have parental DNA, and the presence of unbalanced embryos. This works in three phases: (i) informative SNPs within 5 Mb of the breakpoints on each of the two chromosomes are identified on parental DNA; (ii) comprehensive chromosome screening on embryo biopsies is performed (unbalanced embryos serve as linkage analysis); and (iii) the normal/balanced embryos are evaluated according to the information gathered from unbalanced embryo genotypes. This method relies on the availability of the presence of unbalanced embryos. In these studies, the implantation potentials of carrier versus normal embryos were not different (P = 0.33).
Genetics of Endocrine Disorders and Diabetes Mellitus
Published in George H. Gass, Harold M. Kaplan, Handbook of Endocrinology, 2020
Bess Adkins Marshall, Abby Solomon Hollander
A locus on chromosome 20 in or near the adenosine deaminase (ADA) gene locus cosegregates with MODY in some families.136,137 These families do not show linkage between MODY and the glucokinase gene. The chromosome 20 locus was not associated with MODY in a study of Japanese families112 or in a study of two pedigrees, one from Denmark and another from Britain which was subsequently found to show a linkage of the glucokinase gene.97 A study of 15 French MODY families did not reveal a linkage between the ADA locus and MODY.82 Although the linkage to the chromosome 20 locus is strong in those families in which it has been found, it has been found in few families. Therefore, this locus may be a less common cause of MODY than defects in glucokinase. The chromosome 20 gene product that is defective is not yet known.
Microdeletion Syndromes
Published in Merlin G. Butler, F. John Meaney, Genetics of Developmental Disabilities, 2019
Gopalrao V. N. Velagaleti, Nancy J. Carpenter
On the basis of several published reports showing cytogenetically visible deletions (Fig. 2) or translocations involving the short arm of chromosome 20, AGS was mapped to 20p12 (12). A cell surface protein that functions as a key signaling molecule called Jagged 1 (JAG1) was identified by two groups to be physically located within this region, commonly deleted on chromosome 20p. Mutations in JAG1 were found in AGS patients in multiple families and thus confirming that JAG1 is the AGS disease gene (13,14).
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
Disruption of SPO11 gene can be considered as a potential candidate for spermatogenesis defects. This gene contains 13 exons located on chromosome 20 and in position 20q13.2–13.3 [79]. A critical protein with 396 amino acids is encoded by this gene. The two major isoforms of SPO11, SPO11α (lacking exon 2) and SPO11β, are produced by alternative splicing. This protein plays an important role in the meiosis process, in which DSBs cause interhomolog recombination [80]. DSB meiosis is highly repairable in each cell and helps spontaneously DNA damage. DSBs are created by SPO11 molecule and then the molecule is isolated from DNA and the ‘5ʹ cut ends to produce a single ‘3ʹ end [81]. SPO11 molecule acts as a dimer, that one of the molecules is covalently attached to the end of the DSB [82]. The catalytic activity for the formation of DSBs indicates that SPO11 acts more as a transesterase than an endonuclease. There is a tyrosine residue in the active site of this enzyme that plays a critical role in DSB.
Clinical characteristics and management of Turner patients with a small supernumerary marker chromosome
Published in Gynecological Endocrinology, 2021
Jie Chen, Miao Guo, Min Luo, Shan Deng, Qinjie Tian
With the development of cell biology, new chromosomes with structural abnormalities generally equal in size or smaller than chromosome 20 have been detected by the cytogenetic banding technique. The source or characteristics of the sex chromosomes cannot be identified by conventional banding cytogenetic technology, and they are now known as small supernumerary marker chromosomes (sSMCs) [5,6] and reported as + mar in a karyotype analysis. sSMC can be present in normal karyotypes, in numerically abnormal karyotypes (such as TS or Down’s syndrome), or in structurally abnormal but balanced karyotypes (such as Roche translocation and ring chromosomes) [6]. TS with sSMC usually exists in the form of a chimera, and sSMC has a unique formation mode and source characteristics. Therefore, identifying the source of sSMC and analyzing the correlation between sSMC and phenotype will not only contribute to the study of the origins of sSMC, but also have important clinical significance for the management and prognosis of TS patients with sSMC.
Particulate matter less than 10 μm (PM10) activates cancer related genes in lung epithelial cells
Published in Inhalation Toxicology, 2020
Daeun Kang, In Beom Jung, Su Yel Lee, Se Jin Park, Sun Jung Kwon, Dong Ho Park, Ji Woong Son
BPIFA2 encodes a member of the PLUNC protein family (PLUNC – palate, lung, and nasal epithelium clone). BPIFA2 is known as a short PLUNC-2 (SPLUNC2). It is present in a gene cluster on chromosome 20 (Bingle and Bingle 2000; Bingle and Craven 2002; Bingle et al. 2011). Members of this family have been proposed to play a role in local antibacterial responses in the nose, mouth and upper respiratory pathway (Geetha et al. 2003; Gorr et al. 2011). Vladimir Prokopovic et al. (2014) reported that BPIFA2 protein has an antibacterial effect. We thought that BPIFA2 was upregulated to protect the body from the inflammatory response of PM10.