Acrocentric Chromosome

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Shuo Zhang - One of the best experts on this subject based on the ideXlab platform.

  • analysis of segregation patterns of quadrivalent structures and the effect on genome stability during meiosis in reciprocal translocation carriers
    Human Reproduction, 2018
    Co-Authors: Daru Lu, Jialong Wu, Jing Fu, Junping Wu, Shuo Zhang, Jing Zhou, Yueping Zhang
    Abstract:

    STUDY QUESTION: Do specific factors affect the segregation patterns of a quadrivalent structure and can the quadrivalent affect genome stability during meiosis? SUMMARY ANSWER: Meiotic segregation patterns can be affected by the carrier's gender and age, location of breakpoints and Chromosome type, and the quadrivalent structure can increase genome instability during meiosis. WHAT IS KNOWN ALREADY: Carriers of reciprocal translocations have an increased genetic reproductive risk owing to the complex segregation patterns of a quadrivalent structure. However, the results of previous studies on the factors that affect segregation patterns seem to be contradictory, and the effect of a quadrivalent on genome stability during meiosis is unknown. STUDY DESIGN, SIZE, DURATION: We designed a retrospective study to analyze the segregation patterns of 24 Chromosomes from reciprocal translocation and non-translocation patients. Data for 356 reciprocal translocation carriers and 53 patients with the risk to transmit monogenic inherited disorders (RTMIDs) undergoing PGD-single nucleotide polymorphism array analysis were collected. The study was performed between March 2014 and July 2017. PARTICIPANTS/MATERIALS, SETTING, METHODS: Segregation patterns of a quadrivalent in 1842 blastocysts from 466 assisted reproduction cycles of reciprocal translocation carriers were analyzed according to the location of Chromosome breakpoints, the carrier's gender and age, and Chromosome type. In addition, to analyze the effect of quadrivalent structure on genome stability, segregation products of Chromosomes which are not involved in the translocation from translocation carriers were compared with those of 23 pairs of Chromosomes in 318 blastocysts from 72 assisted reproduction cycles of patients with RTMIDs. MAIN RESULTS AND THE ROLE OF CHANCE: The percentage of adjacent-2 products with severe asymmetric quadrivalent was significantly higher than those with mild asymmetric quadrivalent (P = 0.020) while, in contrast, the incidence of 4:0/others was lower (P = 0.030). The frequencies of adjacent-1, adjacent-2 and 3:1 products differed between male and female carriers (P < 0.001, P = 0.015 and P = 0.001, respectively), and also for adjacent-1 and 4:0/others products in young versus older carriers (P = 0.04 and P = 0.002, respectively). In addition, adjacent-1 products of a quadrivalent with an Acrocentric Chromosome were significantly higher than those of a quadrivalent without an Acrocentric Chromosome (P = 0.001). Moreover, a quadrivalent could significantly increase the frequencies of abnormal Chromosomes compared to patients with RTMIDs (P = 0.048, odds ratio (OR) = 1.43, 95% CI = 1.01-2.43), especially for the male carriers (P = 0.018, OR = 1.58, 95% CI = 1.08-2.25). In contrast, for older carriers, no difference was found in both aneuploidy and segmental anomalies compared to patients with RTMIDs. LIMITATIONS, REASONS FOR CAUTION: The study contained appropriate controls, yet the analysis was limited by a small number of control patients and embryos. WIDER IMPLICATIONS OF THE FINDINGS: Until now, there had been no definite report about the effect of quadrivalents on genome stability in reciprocal translocation carriers compared with control samples, and in the present study the large sample size ensured a detailed analysis of factors with a possible impact on segregation patterns. These data provide a better insight into the meiotic mechanisms involved in non-disjunction events in gametes from reciprocal translocation carriers. In addition, our results will help to provide each reciprocal translocation carrier couple undergoing PGD with more appropriate genetic counseling and a better understanding of the large numbers of abnormal embryos with Chromosome aneuploidy. STUDY FUNDING/COMPETING INTEREST(S): The research was supported by the Research Funding of Shanghai Ji Ai Genetics & IVF Institute and the authors declare a lack of competing interests in this study.

Y Rumpler - One of the best experts on this subject based on the ideXlab platform.

Yueping Zhang - One of the best experts on this subject based on the ideXlab platform.

  • analysis of segregation patterns of quadrivalent structures and the effect on genome stability during meiosis in reciprocal translocation carriers
    Human Reproduction, 2018
    Co-Authors: Daru Lu, Jialong Wu, Jing Fu, Junping Wu, Shuo Zhang, Jing Zhou, Yueping Zhang
    Abstract:

    STUDY QUESTION: Do specific factors affect the segregation patterns of a quadrivalent structure and can the quadrivalent affect genome stability during meiosis? SUMMARY ANSWER: Meiotic segregation patterns can be affected by the carrier's gender and age, location of breakpoints and Chromosome type, and the quadrivalent structure can increase genome instability during meiosis. WHAT IS KNOWN ALREADY: Carriers of reciprocal translocations have an increased genetic reproductive risk owing to the complex segregation patterns of a quadrivalent structure. However, the results of previous studies on the factors that affect segregation patterns seem to be contradictory, and the effect of a quadrivalent on genome stability during meiosis is unknown. STUDY DESIGN, SIZE, DURATION: We designed a retrospective study to analyze the segregation patterns of 24 Chromosomes from reciprocal translocation and non-translocation patients. Data for 356 reciprocal translocation carriers and 53 patients with the risk to transmit monogenic inherited disorders (RTMIDs) undergoing PGD-single nucleotide polymorphism array analysis were collected. The study was performed between March 2014 and July 2017. PARTICIPANTS/MATERIALS, SETTING, METHODS: Segregation patterns of a quadrivalent in 1842 blastocysts from 466 assisted reproduction cycles of reciprocal translocation carriers were analyzed according to the location of Chromosome breakpoints, the carrier's gender and age, and Chromosome type. In addition, to analyze the effect of quadrivalent structure on genome stability, segregation products of Chromosomes which are not involved in the translocation from translocation carriers were compared with those of 23 pairs of Chromosomes in 318 blastocysts from 72 assisted reproduction cycles of patients with RTMIDs. MAIN RESULTS AND THE ROLE OF CHANCE: The percentage of adjacent-2 products with severe asymmetric quadrivalent was significantly higher than those with mild asymmetric quadrivalent (P = 0.020) while, in contrast, the incidence of 4:0/others was lower (P = 0.030). The frequencies of adjacent-1, adjacent-2 and 3:1 products differed between male and female carriers (P < 0.001, P = 0.015 and P = 0.001, respectively), and also for adjacent-1 and 4:0/others products in young versus older carriers (P = 0.04 and P = 0.002, respectively). In addition, adjacent-1 products of a quadrivalent with an Acrocentric Chromosome were significantly higher than those of a quadrivalent without an Acrocentric Chromosome (P = 0.001). Moreover, a quadrivalent could significantly increase the frequencies of abnormal Chromosomes compared to patients with RTMIDs (P = 0.048, odds ratio (OR) = 1.43, 95% CI = 1.01-2.43), especially for the male carriers (P = 0.018, OR = 1.58, 95% CI = 1.08-2.25). In contrast, for older carriers, no difference was found in both aneuploidy and segmental anomalies compared to patients with RTMIDs. LIMITATIONS, REASONS FOR CAUTION: The study contained appropriate controls, yet the analysis was limited by a small number of control patients and embryos. WIDER IMPLICATIONS OF THE FINDINGS: Until now, there had been no definite report about the effect of quadrivalents on genome stability in reciprocal translocation carriers compared with control samples, and in the present study the large sample size ensured a detailed analysis of factors with a possible impact on segregation patterns. These data provide a better insight into the meiotic mechanisms involved in non-disjunction events in gametes from reciprocal translocation carriers. In addition, our results will help to provide each reciprocal translocation carrier couple undergoing PGD with more appropriate genetic counseling and a better understanding of the large numbers of abnormal embryos with Chromosome aneuploidy. STUDY FUNDING/COMPETING INTEREST(S): The research was supported by the Research Funding of Shanghai Ji Ai Genetics & IVF Institute and the authors declare a lack of competing interests in this study.

Asangla Ao - One of the best experts on this subject based on the ideXlab platform.

  • Chromosome segregation analysis in human embryos obtained from couples involving male carriers of reciprocal or robertsonian translocation
    PLOS ONE, 2012
    Co-Authors: Ahmet Yilmaz, Xiao Yun Zhang, Jintae Chung, Hananel Holzer, Asangla Ao
    Abstract:

    The objective of this study was to investigate the frequency and type of Chromosome segregation patterns in cleavage stage embryos obtained from male carriers of Robertsonian (ROB) and reciprocal (REC) translocations undergoing preimplantation genetic diagnosis (PGD) at our reproductive center. We used FISH to analyze Chromosome segregation in 308 day 3 cleavage stage embryos obtained from 26 patients. The percentage of embryos consistent with normal or balanced segregation (55.1% vs. 27.1%) and clinical pregnancy (62.5% vs. 19.2%) rates were higher in ROB than the REC translocation carriers. Involvement of non-Acrocentric Chromosome(s) or terminal breakpoint(s) in reciprocal translocations was associated with an increase in the percent of embryos consistent with adjacent 1 but with a decrease in 3∶1 segregation. Similar results were obtained in the analysis of nontransferred embryos donated for research. 3∶1 segregation was the most frequent segregation type in both day 3 (31%) and spare (35%) embryos obtained from carriers of t(11;22)(q23;q11), the only non-random REC with the same breakpoint reported in a large number of unrelated families mainly identified by the birth of a child with derivative Chromosome 22. These results suggest that Chromosome segregation patterns in day 3 and nontransferred embryos obtained from male translocation carriers vary with the type of translocation and involvement of Acrocentric Chromosome(s) or terminal breakpoint(s). These results should be helpful in estimating reproductive success in translocation carriers undergoing PGD.

Chenming Xu - One of the best experts on this subject based on the ideXlab platform.

  • meiotic segregation analysis of embryos from reciprocal translocation carriers in pgd cycles
    Reproductive Biomedicine Online, 2012
    Co-Authors: Yinghui Ye, Yuli Qian, Chenming Xu
    Abstract:

    Abstract Meiotic segregation patterns of 278 embryos from 41 preimplantation genetic diagnosis cycles of 34 reciprocal translocation carriers were analysed to investigate whether some characteristics of reciprocal translocation, including terminal breakpoints, Acrocentric Chromosome or carrier gender, are related to meiotic segregation patterns. The incidence of normal/balanced karyotypes in translocations with terminal breakpoints was significantly lower than those without terminal breakpoints (6.5% versus 14.4%, P =0.005). The incidences of adjacent-1 (21.0% versus 29.6%), adjacent-2 (16.1% versus 11.1%) and 3:1 (41.9% versus 30.6%) segregation were not statistically significantly different in translocations with terminal breakpoints versus those without. Translocation with Acrocentric Chromosomes showed a significantly lower rate of 2:2 segregation (39.2% versus 60.2%, P =0.001) and a higher rate of 3:1 segregation (43.1% versus 27.3%, P =0.005) than those without Acrocentric Chromosomes. The incidence of 2:2 segregation was significantly higher in male than in female carriers (58.2% versus 45.0%, P =0.019). This study suggested that reciprocal translocation involving terminal breakpoints resulted in a lower rate of normal/balanced karyotype in preimplantation embryos. Some characteristics of reciprocal translocation, such as terminal breakpoints, Acrocentric Chromosome and carrier gender, are related to the segregation patterns. Reciprocal translocations result from exchange of two terminal segments from different Chromosomes. During meiosis I of reciprocal translocations, translocated Chromosomes and their normal homologues segregate by alternate, adjacent-I, adjacent-II, 3:1 or 4:0 modes. Genetically normal/balanced gametes are only produced by alternate segregation while other segregation modes would lead to the production of chromosomally unbalanced gametes. Preimplantation genetic diagnosis (PGD) has been offered to carriers of reciprocal translocations to reduce the frequency of spontaneous abortions and affected newborns by selecting chromosomally normal/balanced embryos. In the present study, meiotic segregation patterns of 278 embryos from 41 PGD cycles of 34 reciprocal translocation carriers were analysed to investigate whether some characteristics of reciprocal translocation, including terminal breakpoints, Acrocentric Chromosome or carrier gender are related to meiotic segregation patterns. The incidence of normal/balanced karyotypes in translocations with terminal breakpoints was significantly lower than those without terminal breakpoints. The incidence of adjacent-1 segregation was lower and the incidences of adjacent-2 and 3:1 segregation were higher in translocations with terminal breakpoints. Translocation with Acrocentric Chromosomes showed a significantly lower rate of 2:2 segregation and a higher rate of 3:1 segregation than those without Acrocentric Chromosomes. The incidence of 2:2 segregation was significantly higher in male than in female carriers. Our study suggests that reciprocal translocations involving terminal breakpoints resulted in a lower rate of normal/balanced karyotype in preimplantation embryos. Some characteristics of reciprocal translocation, such as terminal breakpoints, Acrocentric Chromosome and carrier gender, are related to the segregation patterns.