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Muñoz E, Bronet F, Lledo B, Palacios-Verdú G, Martinez-Rocca L, Altmäe S, Pla J. To transfer or not to transfer: the dilemma of mosaic embryos - a narrative review. Reprod Biomed Online 2024; 48:103664. [PMID: 38408811 DOI: 10.1016/j.rbmo.2023.103664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 10/19/2023] [Accepted: 10/30/2023] [Indexed: 02/28/2024]
Abstract
A frequent finding after preimplantation genetic diagnostic testing for aneuploidies using next-generation sequencing is an embryo that is putatively mosaic. The prevalence of this outcome remains unclear and varies with technical and external factors. Mosaic embryos can be classified by the percentage of cells affected, type of chromosome involvement (whole or segmental), number of affected chromosomes or affected cell type (inner mass cell, trophectoderm or both). The origin of mosaicism seems to be intrinsic as a post-zygotic mitotic error, but some external factors can play a role. As experience has increased with the transfer of mosaic embryos, clinical practice has gradually become more flexible in recent years. Nevertheless, clinical results show lower implantation, pregnancy and clinical pregnancy rates and higher miscarriage rates with mosaic embryo transfer when compared with the transfer of euploid embryos. Prenatal diagnosis is highly recommended after the transfer of mosaic embryos. This narrative review is intended to serve as reference material for practitioners in reproductive medicine who must manage a mosaic embryo result after preimplantation genetic testing for aneuploidies.
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Affiliation(s)
- Elkin Muñoz
- Reproductive Medicine, IVIRMA Vigo, Vigo, Spain; Department of Obstetrics and Gynecology, University of Cauca, Popayan, Colombia
| | | | | | - Gabriela Palacios-Verdú
- Unit of Genomic Medicine, Department of Obstetrics, Gynecology and Reproductive Medicine, Institut Universitari Quirón Dexeus, Barcelona, Spain
| | | | - Signe Altmäe
- Department of Biochemistry and Molecular Biology, Faculty of Sciences, University of Granada, Granada, Spain; Instituto de Investigación Biosanitaria ibs, Granada, Granada, Spain; Division of Obstetrics and Gynecology, Department of Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden
| | - Josep Pla
- Reproductive Genetics Unit, IVIRMA Global, Barcelona, Spain.
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Abnormal early cleavage events predict early embryo demise: sperm oxidative stress and early abnormal cleavage. Sci Rep 2014; 4:6598. [PMID: 25307782 PMCID: PMC4194434 DOI: 10.1038/srep06598] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Accepted: 09/18/2014] [Indexed: 12/16/2022] Open
Abstract
Human embryos resulting from abnormal early cleavage can result in aneuploidy and failure to develop normally to the blastocyst stage. The nature of paternal influence on early embryo development has not been directly demonstrated although many studies have suggested effects from spermatozoal chromatin packaging, DNA damage, centriolar and mitotic spindle integrity, and plasma membrane integrity. The goal of this study was to determine whether early developmental events were affected by oxidative damage to the fertilizing sperm. Survival analysis was used to compare patterns of blastocyst formation based on P2 duration. Kaplan-Meier survival curves demonstrate that relatively few embryos with short (<1 hr) P2 times reached blastocysts, and the two curves diverged beginning on day 4, with nearly all of the embryos with longer P2 times reaching blastocysts by day 6 (p < .01). We determined that duration of the 2nd to 3rd mitoses were sensitive periods in the presence of spermatozoal oxidative stress. Embryos that displayed either too long or too short cytokineses demonstrated an increased failure to reach blastocyst stage and therefore survive for further development. Although paternal-derived gene expression occurs later in development, this study suggests a specific role in early mitosis that is highly influenced by paternal factors.
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Ly KD, Agarwal A, Nagy ZP. Preimplantation genetic screening: does it help or hinder IVF treatment and what is the role of the embryo? J Assist Reprod Genet 2011; 28:833-49. [PMID: 21743973 DOI: 10.1007/s10815-011-9608-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2010] [Accepted: 06/28/2011] [Indexed: 12/31/2022] Open
Abstract
Despite an ongoing debate over its efficacy, preimplantation genetic screening (PGS) is increasingly being used to detect numerical chromosomal abnormalities in embryos to improve implantation rates after IVF. The main indications for the use of PGS in IVF treatments include advanced maternal age, repeated implantation failure, and recurrent pregnancy loss. The success of PGS is highly dependent on technical competence, embryo culture quality, and the presence of mosaicism in preimplantation embryos. Today, cleavage stage biopsy is the most commonly used method for screening preimplantation embryos for aneuploidy. However, blastocyst biopsy is rapidly becoming the more preferred method due to a decreased likelihood of mosaicism and an increase in the amount of DNA available for testing. Instead of using 9 to 12 chromosome FISH, a 24 chromosome detection by aCGH or SNP microarray will be used. Thus, it is advised that before attempting to perform PGS and expecting any benefit, extended embryo culture towards day 5/6 should be established and proven and the clinical staff should demonstrate competence with routine competency assessments. A properly designed randomized control trial is needed to test the potential benefits of these new developments.
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Affiliation(s)
- Kim Dao Ly
- Center for Reproductive Medicine, Cleveland Clinic, Cleveland, Ohio, USA.
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First successful pregnancy following PGD for chromosome translocation on embryos generated from in-vitro matured oocytes: a case report. Reprod Biomed Online 2010; 22:371-5. [PMID: 21324743 DOI: 10.1016/j.rbmo.2010.11.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Revised: 10/29/2010] [Accepted: 11/17/2010] [Indexed: 11/22/2022]
Abstract
As far as is known, this is the first report of a successful pregnancy outcome following preimplantation genetic diagnosis for a chromosome translocation in embryos generated from in-vitro matured oocytes. A couple presented to the study clinic where the female partner was a carrier of the reciprocal chromosome translocation 46,XX,t(1;20)(p36.1;p12.2) with three consecutive pregnancy terminations due to either fetal abnormality or unbalanced translocation products detected in the conceptus. Under routine ultrasound investigation she was diagnosed with polycystic ovaries. The patient underwent an in-vitro maturation/preimplantation genetic diagnosis cycle where the immature oocytes were matured in vitro and fertilized by intracytoplasmic sperm injection. Day-3 embryos were screened for the chromosome abnormality by fluorescent in-situ hybridization. A single embryo diagnosed as chromosomally normal/balanced was transferred on day 5 and resulted in the birth of a healthy child.
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Marchetti F, Bishop J, Lowe X, Wyrobek AJ. Chromosomal mosaicism in mouse two-cell embryos after paternal exposure to acrylamide. Toxicol Sci 2008; 107:194-205. [PMID: 18930949 DOI: 10.1093/toxsci/kfn209] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Chromosomal mosaicism in human preimplantation embryos is a common cause of spontaneous abortions, however, our knowledge of its etiology is limited. We used multicolor fluorescence in situ hybridization painting to investigate whether paternally transmitted chromosomal aberrations result in mosaicism in mouse two-cell embryos. Paternal exposure to acrylamide, an important industrial chemical also found in tobacco smoke and generated during the cooking process of starchy foods, produced significant increases in chromosomally defective two-cell embryos, however, the effects were transient primarily affecting the postmeiotic stages of spermatogenesis. Comparisons with our previous study of zygotes demonstrated similar frequencies of chromosomally abnormal zygotes and two-cell embryos suggesting that there was no apparent selection against numerical or structural chromosomal aberrations. However, the majority of affected two-cell embryos were mosaics showing different chromosomal abnormalities in the two blastomeric metaphases. Analyses of chromosomal aberrations in zygotes and two-cell embryos showed a tendency for loss of acentric fragments during the first mitotic division of embryogenesis, whereas both dicentrics and translocations apparently underwent proper segregation. These results suggest that embryonic development can proceed up to the end of the second cell cycle of development in the presence of abnormal paternal chromosomes and that even dicentrics can persist through cell division. The high incidence of chromosomally mosaic two-cell embryos suggests that the first mitotic division of embryogenesis is prone to missegregation errors and that paternally transmitted chromosomal abnormalities increase the risk of missegregation leading to embryonic mosaicism.
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Affiliation(s)
- Francesco Marchetti
- Biosciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, USA
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Delhanty JDA. Mechanisms of aneuploidy induction in human oogenesis and early embryogenesis. Cytogenet Genome Res 2006; 111:237-44. [PMID: 16192699 DOI: 10.1159/000086894] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2004] [Accepted: 02/25/2005] [Indexed: 11/19/2022] Open
Abstract
The mechanisms of aneuploidy induction in human oogenesis mainly involve nondisjunction arising during the first and second meiotic divisions. Nondisjunction equally affects both whole chromosomes and chromatids, in the latter case it is facilitated by "predivision" or precocious centromere division. Karyotyping and CGH studies show an excess of hypohaploidy, which is confirmed in studies of preimplantation embryos, providing evidence in favour of anaphase lag as a mechanism. Preferential involvement of the smaller autosomes has been clearly shown but the largest chromosomes are also abnormal in many cases. Overall, the rate of chromosomal imbalance in oocytes from women aged between 30 and 35 has been estimated at 11% from recent karyotyping data but accruing CGH results suggest that the true figure should be considerably higher. Clear evidence has been obtained in favour of germinal or gonadal mosaicism as a predisposing factor. Constitutional aneuploidy in embryos is most frequent for chromosomes 22, 16, 21 and 15; least frequently involved are chromosomes 14, X and Y, and 6. However, embryos of women under 37 are far more likely to be affected by mosaic aneuploidy, which is present in over 50% of 3-day-old embryos. There are two main types, diploid/aneuploid and chaotic mosaics. Chaotic mosaics arise independently of maternal age and may be related to centrosome anomalies and hence of male origin. Aneuploid mosaics most commonly arise by chromosome loss, followed by chromosome gain and least frequently by mitotic nondisjunction. All may be related to maternal age as well as to lack of specific gene products in the embryo. Partial aneuploidy as a result of chromosome breakage affects a minimum of 10% of embryos.
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Affiliation(s)
- J D A Delhanty
- UCL Centre for Preimplantation Diagnosis, Department of Obstetrics & Gynaecology, University College London, London, UK.
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Bielanska M, Jin S, Bernier M, Tan SL, Ao A. Diploid-aneuploid mosaicism in human embryos cultured to the blastocyst stage. Fertil Steril 2005; 84:336-42. [PMID: 16084874 DOI: 10.1016/j.fertnstert.2005.03.031] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2004] [Revised: 03/21/2005] [Accepted: 03/21/2005] [Indexed: 10/25/2022]
Abstract
OBJECTIVE To examine diploid-aneuploid mosaicism in human in vitro cultured blastocysts. DESIGN A laboratory study on spare blastocysts from an IVF program. SETTING University hospital laboratory. PATIENTS(S) Forty-three couples undergoing IVF or intracytoplasmic sperm injection. INTERVENTION(S) Ninety-one blastocysts were spread for fluorescence in situ hybridization using the HCl-Tween 20 method. A total of 6,664 nuclei were analyzed for aneuploidy using fluorescent DNA probes specific to chromosomes 2, 7, and 18. MAIN OUTCOME MEASURE(S) The proportion of aneuploid cells within each blastocyst. RESULTS(S) The incidence of diploid-aneuploid mosaicism among 91 blastocysts examined was 17.6%. All of the mosaic blastocysts were abnormal for only one of the three chromosomes tested, with the incidence of involvement of chromosomes 2, 7, and 18 being 3.3%, 8.8%, and 5.5%, respectively. The majority of the mosaic blastocysts had low proportions of aneuploid cells. Ten of the 16 (62.5%) affected blastocysts were of morphology compatible with implantation. CONCLUSION(S) A considerable proportion of human IVF blastocysts show a form of mosaicism that has been observed in fetal and placental tissues. This mosaicism often arises at the final stage of preimplantation development in vitro and is present in blastocysts of morphology compatible with implantation.
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Affiliation(s)
- Magdalena Bielanska
- McGill Reproductive Centre, Royal Victoria Hospital, McGill University, Montreal, Quebec, Canada
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Gleicher N, Tang YX. Blastomere transplantation in human embryos may be a treatment for single gene diseases. Fertil Steril 2004; 81:977-81. [PMID: 15066451 DOI: 10.1016/j.fertnstert.2003.08.055] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2003] [Revised: 08/15/2003] [Accepted: 08/15/2003] [Indexed: 11/21/2022]
Abstract
OBJECTIVE To determine whether human embryos accept blastomere transplants and integrate them normally into the architecture of the developing embryo. DESIGN A human blastomere transplantation model, involving 44 cryopreserved embryos that were specifically donated to research. SETTING Academically affiliated private infertility center. PATIENT(S) Forty-four human embryos. INTERVENTION(S) In 21 experiments, one, two, or three blastomeres were transplanted, using standard microsurgical techniques that are widely used in preimplantation genetic diagnosis (PGD). Embryos were thawed and gender was determined, using established PGD techniques. Male (xy) blastomeres were then transplanted into female (xx) day 3 embryos, and the xy cells were tracked through blastocyst stage (days 5-6) and into the hatching period (day 6), using fluorescent in situ hybridization (FISH). MAIN OUTCOME MEASURE(S) Degree and location of xy cell integration into xx embryos. RESULT(S) High-quality recipient embryos (with 4 to 10 cells) developed uniformly into normal blastocyst stage embryos in 12 of 12 experiments (100%) and integrated donor blastomeres into their architecture, with apparently even distribution of daughter cells; this integration was documented in inner cell mass as well as in trophoectoderm. The intensity of this distribution appeared to correlate with the number of blastomeres transferred. Among nine abnormally developing embryos, only three (33%) demonstrated a normal distribution of offspring donor cells. CONCLUSION(S) High-quality embryos appear to have the ability to integrate donor blastomeres. Because the treatment of single gene diseases does not require successful treatment of all cells, blastomere transplantation could be explored as a treatment option, which also would greatly enhance efficiency and utilization of preimplantation genetic diagnosis.
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Simopoulou M, Harper JC, Fragouli E, Mantzouratou A, Speyer BE, Serhal P, Ranieri DM, Doshi A, Henderson J, Rodeck CH, Delhanty JDA. Preimplantation genetic diagnosis of chromosome abnormalities: implications from the outcome for couples with chromosomal rearrangements. Prenat Diagn 2003; 23:652-62. [PMID: 12913872 DOI: 10.1002/pd.662] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVES Chromosomal rearrangements can lead to infertility or repeated spontaneous or induced abortions. The use of preimplantation genetic diagnosis (PGD) allows the selected transfer of chromosomally balanced embryos. The aim of this study was to carry out detailed analysis of the outcome of 11 PGD cycles for 8 patients carrying various chromosomal rearrangements. METHODS Patients underwent routine in vitro fertilisation with biopsy of embryos on day 3. Specific fluorescent in situ hybridisation protocols were developed for each couple. Embryo transfer was possible in all 11 cycles. RESULTS The outcome was four pregnancies, leading to three live births and one biochemical pregnancy. Post-zygotic mosaicism was detected in 75% of untransferred embryos, the majority of which were chaotic. Detailed follow-up and analysis provided evidence for the co-existence of chromosomally balanced and abnormal cells in six embryos. The mechanisms involved included chromosome breakage and loss of material. CONCLUSIONS Biopsy and analysis of two blastomeres, where possible, reduced the risk of misdiagnosis in cases of balanced/aneuploid mosaics. The three live births achieved for the eight couples treated in this series, despite the poor history in almost all cases, is further proof that a policy of biopsying two cells from embryos consisting of six or more cells and a single cell from four- or five-cell embryos is compatible with a positive outcome.
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Affiliation(s)
- M Simopoulou
- UCL Centre for Preimplantation Genetic Diagnosis and Assisted Conception Unit, Department of Obstetrics and Gynaecology, University College London, London, UK
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Bielanska M, Tan SL, Ao A. Chromosomal information derived from single blastomeres isolated from cleavage-stage embryos and cultured in vitro. Fertil Steril 2003; 79:1304-11. [PMID: 12798875 DOI: 10.1016/s0015-0282(03)00356-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To evaluate the potential of proliferation of single blastomeres isolated from human cleavage-stage embryos for use in preimplantation genetic diagnosis of chromosomal abnormalities. DESIGN A laboratory study of chromosomal content of blastomeres isolated from embryos of patients from an in vitro fertilization program. SETTING University hospital laboratory. PATIENT(S) Couples undergoing IVF or ICSI. INTERVENTION(S) Blastomeres were isolated from normally fertilized cleavage-stage human embryos, cultured in vitro or fixed immediately, and analyzed by fluorescence in situ hybridization (FISH) probes. MAIN OUTCOME MEASURES Chromosomal information yielded by blastomeres cultured in vitro compared with those obtained from blastomeres that were processed for chromosomal analysis directly after isolation. RESULT(S) The percentage of cultured blastomeres that produced FISH results was significantly lower than the percentage of blastomeres processed for FISH directly after isolation (72% vs. 90%). Lack of FISH results from cultured cells, which in most cases was related to nuclear anomalies, was significantly more frequent among nondivided than divided blastomeres (39% vs. 21%). Both cultured and noncultured cells showed diploid, aneuploid and polyploid chromosome complements on FISH. Compared with directly processed cells, cultured cells yielded a higher proportion of polyploid patterns (22.9% vs. 6.1%). Of the cultured blastomeres that divided, 18% produced progeny with mosaicism. CONCLUSION(S) Although blastomere culture may increase the number of cells available for chromosomal analysis, the high frequency of nuclear defects and the occurrence of polyploidy and mosaicism among cultured cells discourage the use of blastomere isolation and proliferation strategy for use in preimplantation genetic diagnosis.
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Affiliation(s)
- Magdalena Bielanska
- Department of Obstetrics and Gynecology, Royal Victoria Hospital, Montreal, Quebec, Canada
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Current awareness in prenatal diagnosis. Prenat Diagn 2002; 22:843-9. [PMID: 12356028 DOI: 10.1002/pd.272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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