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1.
PLoS Genet ; 18(8): e1010377, 2022 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-36037166

RESUMEN

[This corrects the article DOI: 10.1371/journal.pgen.1003025.].

2.
Reprod Biomed Online ; 37(2): 136-144, 2018 08.
Artículo en Inglés | MEDLINE | ID: mdl-29853423

RESUMEN

RESEARCH QUESTION: Mutations of the beta-globin gene (HBB) cause beta-thalassaemia and sickle cell anaemia. These are the most common cause of severe inherited disease in humans. Traditional preimplantation genetic testing protocols for detecting HBB mutations frequently involve labour intensive, patient-specific test designs owing to the wide diversity of disease-associated HBB mutations. We, therefore, asked the question whether a universally applicable preimplantation genetic testing method can be developed to test for HBB gene mutations. DESIGN: A multiplex polymerase chain reaction protocol was designed, allowing simultaneous amplification of multiple overlapping DNA fragments encompassing the entire HBB gene sequence in addition to 17 characterized, closely linked single nucleotide polymorphisms (SNP). Amplicons were then analysed using a next-generation sequencing method, revealing mutations and SNP genotypes. The protocol was extensively validated, optimized and eventually clinically applied on whole-genome amplified DNA derived from embryos of three couples carrying different combinations of beta-thalassaemia mutations. RESULTS: The HBB mutation status and associated SNP haplotypes were successfully determined in all 21 embryos. Analysis of 141 heterozygous sites showed no instances of allele dropout and the test displayed 100% concordance compared with the results obtained from karyomapping. This suggests that the combination of trophectoderm biopsy and highly sensitive next-generation sequencing may provide superior accuracy than typically achieved using traditional preimplantation genetic testing methods. Importantly, no patient-specific test design or optimization was needed. CONCLUSIONS: It is hoped that protocols that deliver almost universally applicable low-cost tests, without compromising diagnostic accuracy, will improve patient access to preimplantation genetic testing, especially in less affluent parts of the world.


Asunto(s)
Anemia de Células Falciformes/diagnóstico , Blastocisto , Pruebas Genéticas/métodos , Secuenciación de Nucleótidos de Alto Rendimiento , Diagnóstico Preimplantación/métodos , Talasemia beta/diagnóstico , Alelos , Anemia de Células Falciformes/genética , Femenino , Genotipo , Humanos , Mutación , Embarazo , Talasemia beta/genética
3.
Reprod Biomed Online ; 35(3): 264-271, 2017 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-28648921

RESUMEN

This study aimed to determine whether karyomapping can be applied to couples requiring preimplantation genetic diagnosis (PGD) for single gene disorder (SGD) and/or chromosomal rearrangement. 75/82 (91.5%) and 6/82 (7.3%) couples were referred for autosomal SGD and X-linked disease, respectively. One couple (1.2%) was referred for SGD and chromosomal rearrangement. Of 608 embryos, 146 (24%, 95% CI 21-28) day-3 and 462 (76%, 95% CI 72-79) blastocyst biopsies were performed. A total of 81 embryo transfers were performed; 16/81 (20%) were following day-3 embryo biopsy, 65/81 (80%) were following blastocyst biopsy and cryopreserved embryo transfer. Of 81 embryo transfers with known pregnancy outcome, 51 (63%, 95% CI 52-73) were on-going pregnancies, 6/81 (7%, 95% CI 3-15) resulted in first trimester miscarriages and 24/81 (30%, 95% CI 21-40) were failed implantations. Of the 51 on-going pregnancies, 15 (29%, 95% CI 19-43) couples had a singleton live birth at the time of write up. There have been no reports of abnormal prenatal, genetic testing or diagnosis of phenotype at birth. Karyomapping is reliable, efficient and accurate for couples requiring PGD for SGD and/or chromosomal rearrangement. Additionally, it provides aneuploidy screening, minimising risks of miscarriage and implantation failure.


Asunto(s)
Pruebas Genéticas/métodos , Cariotipificación/métodos , Resultado del Embarazo , Diagnóstico Preimplantación/métodos , Adulto , Tasa de Natalidad , Blastocisto/patología , Mapeo Cromosómico/métodos , Transferencia de Embrión , Femenino , Fertilización In Vitro , Enfermedades Genéticas Congénitas/diagnóstico , Enfermedades Genéticas Congénitas/genética , Humanos , Nacimiento Vivo , Masculino , Embarazo , Resultado del Embarazo/genética , Estudios Retrospectivos
4.
Hum Genet ; 136(7): 805-819, 2017 07.
Artículo en Inglés | MEDLINE | ID: mdl-28393271

RESUMEN

Preimplantation genetic testing for aneuploidy (PGT-A) is widely used in IVF and aims to improve outcomes by avoiding aneuploid embryo transfers. Chromosomal mosaicism is extremely common in early development and could affect the efficacy of PGT-A by causing incorrect embryo classification. Recent innovations have allowed accurate mosaicism detection in trophectoderm samples taken from blastocysts. However, there is little data concerning the impact of mosaicism on viability, and the optimal clinical pathway for such embryos is unclear. This study provides new information concerning the extent to which mosaic preimplantation embryos are capable of producing pregnancies and births. Archived trophectoderm biopsy specimens from transferred blastocysts were analyzed using next generation sequencing (NGS). Unlike other PGT-A methods, NGS accurately detects mosaicism in embryo biopsies. 44 mosaic blastocysts were identified. Their clinical outcomes were compared to 51 euploid blastocysts, derived from a well-matched, contemporary control group. Mosaic embryos were associated with outcomes that were significantly poorer than those of the control group: implantation 30.1 versus 55.8% (P = 0.038); miscarriage rate 55.6 versus 17.2% (P = 0.036); and ongoing pregnancy 15.4 versus 46.2% (P = 0.003). 61% of the mosaic errors affected whole chromosomes and 39% were segmental aneuploidies. Embryo viability is compromised by the presence of aneuploid cells. However, a minority of affected embryos can produce successful pregnancies. Hence, such embryos should not necessarily be excluded, but given a lower priority for transfer than those that are fully euploid. It is recommended that pregnancies established after mosaic embryo transfers be subjected to prenatal testing, with appropriate patient counselling.


Asunto(s)
Aneuploidia , Diploidia , Implantación del Embrión , Transferencia de Embrión/métodos , Mosaicismo/embriología , Índice de Embarazo , Adulto , Blastocisto/citología , Blastocisto/metabolismo , Estudios de Casos y Controles , Femenino , Pruebas Genéticas/métodos , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Cariotipificación , Embarazo , Sensibilidad y Especificidad , Análisis de Secuencia de ADN
6.
Reprod Biomed Online ; 33(3): 404-11, 2016 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-27396673

RESUMEN

Recent studies have reported shorter sperm telomere length (STL) in men with idiopathic infertility. The aim of this study was to measure STL in semen samples from men to evaluate whether STL variation is associated with chromosomal abnormality, DNA fragmentation, traditional semen parameters, IVF outcome, or all four factors. A significant correlation between telomere length and diploidy was observed (P = 0.037). Additionally, STL was found to be positively associated with sperm count (P = 0.006); oligospermic samples had particularly short telomeres (0.9 ± 0.1 versus 1.4 ± 0.1; P = 0.0019). The results confirmed a link between sperm DNA fragmentation and aneuploidy, previously proposed (P = 0.009). A negative relationship was demonstrated between sperm concentration and aneuploidy and Sperm DNA framentation (P = 0.03, P < 0.0001, respectively). For a subset of 51 of the 73 sperm samples used for fertilization, IVF outcomes were known. A total of 17.6% of these samples had atypical STLs. None of these samples produced an ongoing pregnancy. In contrast, the pregnancy rate for samples that had STLs in the normal range was 35.7% (P = 0.044). In conclusion, STL has potential as a fast and inexpensive form of sperm quality assessment.


Asunto(s)
Genoma Humano , Análisis de Semen/métodos , Espermatozoides , Telómero/química , Adulto , Aneuploidia , Fragmentación del ADN , Humanos , Infertilidad Masculina/genética , Masculino , Persona de Mediana Edad
7.
Nature ; 534(7607): 383-6, 2016 06 16.
Artículo en Inglés | MEDLINE | ID: mdl-27281217

RESUMEN

Mitochondrial DNA (mtDNA) mutations are maternally inherited and are associated with a broad range of debilitating and fatal diseases. Reproductive technologies designed to uncouple the inheritance of mtDNA from nuclear DNA may enable affected women to have a genetically related child with a greatly reduced risk of mtDNA disease. Here we report the first preclinical studies on pronuclear transplantation (PNT). Surprisingly, techniques used in proof-of-concept studies involving abnormally fertilized human zygotes were not well tolerated by normally fertilized zygotes. We have therefore developed an alternative approach based on transplanting pronuclei shortly after completion of meiosis rather than shortly before the first mitotic division. This promotes efficient development to the blastocyst stage with no detectable effect on aneuploidy or gene expression. After optimization, mtDNA carryover was reduced to <2% in the majority (79%) of PNT blastocysts. The importance of reducing carryover to the lowest possible levels is highlighted by a progressive increase in heteroplasmy in a stem cell line derived from a PNT blastocyst with 4% mtDNA carryover. We conclude that PNT has the potential to reduce the risk of mtDNA disease, but it may not guarantee prevention.


Asunto(s)
ADN Mitocondrial/genética , Enfermedades Mitocondriales/genética , Enfermedades Mitocondriales/prevención & control , Terapia de Reemplazo Mitocondrial/métodos , Técnicas de Transferencia Nuclear , Adulto , Blastocisto/citología , Blastocisto/metabolismo , Núcleo Celular/genética , Núcleo Celular/metabolismo , Citoplasma/genética , Citoplasma/metabolismo , ADN Mitocondrial/análisis , Femenino , Perfilación de la Expresión Génica , Humanos , Masculino , Meiosis , Mitocondrias/genética , Mitocondrias/metabolismo , Enfermedades Mitocondriales/patología , Células Madre/citología , Células Madre/metabolismo , Investigación Biomédica Traslacional , Adulto Joven , Cigoto/citología , Cigoto/metabolismo
8.
PLoS Genet ; 11(6): e1005241, 2015 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-26039092

RESUMEN

Mitochondria play a vital role in embryo development. They are the principal site of energy production and have various other critical cellular functions. Despite the importance of this organelle, little is known about the extent of variation in mitochondrial DNA (mtDNA) between individual human embryos prior to implantation. This study investigated the biological and clinical relevance of the quantity of mtDNA in 379 embryos. These were examined via a combination of microarray comparative genomic hybridisation (aCGH), quantitative PCR and next generation sequencing (NGS), providing information on chromosomal status, amount of mtDNA, and presence of mutations in the mitochondrial genome. The quantity of mtDNA was significantly higher in embryos from older women (P=0.003). Additionally, mtDNA levels were elevated in aneuploid embryos, independent of age (P=0.025). Assessment of clinical outcomes after transfer of euploid embryos to the uterus revealed that blastocysts that successfully implanted tended to contain lower mtDNA quantities than those failing to implant (P=0.007). Importantly, an mtDNA quantity threshold was established, above which implantation was never observed. Subsequently, the predictive value of this threshold was confirmed in an independent blinded prospective study, indicating that abnormal mtDNA levels are present in 30% of non-implanting euploid embryos, but are not seen in embryos forming a viable pregnancy. NGS did not reveal any increase in mutation in blastocysts with elevated mtDNA levels. The results of this study suggest that increased mtDNA may be related to elevated metabolism and are associated with reduced viability, a possibility consistent with the 'quiet embryo' hypothesis. Importantly, the findings suggest a potential role for mitochondria in female reproductive aging and the genesis of aneuploidy. Of clinical significance, we propose that mtDNA content represents a novel biomarker with potential value for in vitro fertilisation (IVF) treatment, revealing chromosomally normal blastocysts incapable of producing a viable pregnancy.


Asunto(s)
Aneuploidia , ADN Mitocondrial/genética , Implantación del Embrión/genética , Adulto , Factores de Edad , Femenino , Humanos
9.
Fertil Steril ; 102(5): 1385-92, 2014 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-25217868

RESUMEN

OBJECTIVE: To develop a microarray platform that allows simultaneous assessment of aneuploidy and quantification of mitochondrial DNA (mtDNA) in human polar bodies and embryos. DESIGN: Optimization and validation applied to cell lines and clinical samples (polar bodies, blastomeres, and trophectoderm biopsies). SETTING: University research laboratory and a preimplantation genetic diagnosis (PGD) reference laboratory. PATIENT(S): Samples from 65 couples who underwent PGD for aneuploidy and/or a single-gene disorder. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): 1) Comparison of aneuploidy screening results obtained with the use of the new microarray with those derived from two well established cytogenetic techniques. 2) mtDNA quantification. 3) Analysis of single-nucleotide polymorphisms. RESULT(S): The fully optimized microarray was estimated to have an accuracy of ≥97% for the detection of individual aneuploidies and to detect 99% of chromosomally abnormal embryos. The microarray was shown to accurately determine relative quantities of mtDNA. Information provided from polymorphic loci was sufficient to allow confirmation that an embryo was derived from specific parents. CONCLUSION(S): It is hoped that methods such as those reported here, which provide information on several aspects of oocyte/embryo genetics, could lead to improved strategies for identifying viable embryos, thereby increasing the likelihood of successful implantation. Additionally, the provision of genotyping information has the potential to reveal DNA contaminants and confirm parental origin of embryos.


Asunto(s)
Aneuploidia , Blastocisto/fisiología , ADN Mitocondrial/genética , Análisis de Secuencia por Matrices de Oligonucleótidos/instrumentación , Cuerpos Polares/fisiología , Polimorfismo de Nucleótido Simple/genética , Diagnóstico Preimplantación/instrumentación , Adulto , Análisis Mutacional de ADN/instrumentación , Diseño de Equipo , Análisis de Falla de Equipo , Femenino , Humanos
10.
Hum Genet ; 132(9): 1001-13, 2013 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-23620267

RESUMEN

Despite the clinical importance of aneuploidy, surprisingly little is known concerning its impact during the earliest stages of human development. This study aimed to shed light on the genesis, progression, and survival of different types of chromosome anomaly from the fertilized oocyte through the final stage of preimplantation development (blastocyst). 2,204 oocytes and embryos were examined using comprehensive cytogenetic methodology. A diverse array of chromosome abnormalities was detected, including many forms never recorded later in development. Advancing female age was associated with dramatic increase in aneuploidy rate and complex chromosomal abnormalities. Anaphase lag and congression failure were found to be important malsegregation causing mechanisms in oogenesis and during the first few mitotic divisions. All abnormalities appeared to be tolerated until activation of the embryonic genome, after which some forms started to decline in frequency. However, many aneuploidies continued to have little impact, with affected embryos successfully reaching the blastocyst stage. Results from the direct analyses of female meiotic divisions and early embryonic stages suggest that chromosome errors present during preimplantation development have origins that are more varied than those seen in later pregnancy, raising the intriguing possibility that the source of aneuploidy might modulate impact on embryo viability. The results of this study also narrow the window of time for selection against aneuploid embryos, indicating that most survive until the blastocyst stage and, since they are not detected in clinical pregnancies, must be lost around the time of implantation or shortly thereafter.


Asunto(s)
Anafase/fisiología , Aneuploidia , Segregación Cromosómica/fisiología , Desarrollo Embrionario/genética , Desarrollo Embrionario/fisiología , Oogénesis/fisiología , Factores de Edad , Anafase/genética , Segregación Cromosómica/genética , Hibridación Genómica Comparativa , Análisis Citogenético , Femenino , Humanos , Oogénesis/genética , Embarazo
11.
PLoS Genet ; 8(10): e1003025, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-23133396

RESUMEN

Balanced chromosomal rearrangements represent one of the most common forms of genetic abnormality affecting approximately 1 in every 500 (0.2%) individuals. Difficulties processing the abnormal chromosomes during meiosis lead to an elevated risk of chromosomally abnormal gametes, resulting in high rates of miscarriage and/or children with congenital abnormalities. It has also been suggested that the presence of chromosome rearrangements may also cause an increase in aneuploidy affecting structurally normal chromosomes, due to disruption of chromosome alignment on the spindle or disturbance of other factors related to meiotic chromosome segregation. The existence of such a phenomenon (an inter-chromosomal effect--ICE) remains controversial, with different studies presenting contradictory data. The current investigation aimed to demonstrate conclusively whether an ICE truly exists. For this purpose a comprehensive chromosome screening technique, optimized for analysis of minute amounts of tissue, was applied to a unique collection of samples consisting of 283 oocytes and early embryos derived from 44 patients carrying chromosome rearrangements. A further 5,078 oocytes and embryos, derived from chromosomally normal individuals of identical age, provided a robust control group for comparative analysis. A highly significant (P = 0.0002) increase in the rate of malsegregation affecting structurally normal chromosomes was observed in association with Robertsonian translocations. Surprisingly, the ICE was clearly detected in early embryos from female carriers, but not in oocytes, indicating the possibility of mitotic rather than the previously suggested meiotic origin. These findings have implications for our understanding of genetic stability during preimplantation development and are of clinical relevance for patients carrying a Robertsonian translocation. The results are also pertinent to other situations when cellular mechanisms for maintaining genetic fidelity are relaxed and chromosome rearrangements are present (e.g. in tumors displaying chromosomal instability).


Asunto(s)
Desarrollo Embrionario/genética , Inestabilidad Genómica , Heterocigoto , Mitosis , Translocación Genética , Adulto , Estudios de Casos y Controles , Segregación Cromosómica , Hibridación Genómica Comparativa , Femenino , Humanos , Masculino , Oocitos/metabolismo
12.
Mol Hum Reprod ; 17(5): 286-95, 2011 May.
Artículo en Inglés | MEDLINE | ID: mdl-21493685

RESUMEN

Female meiosis is comprised by two cell divisions, meiosis I (MI) and II (MII) and two different stages at which the development of the oocyte is temporarily halted. In the case of MI, this pause can potentially last for four to five decades. This added layer of complexity distinguishes female gametogenesis from its male counterpart. The single most important genetic factor impacting human reproductive success is aneuploidy. Aneuploid embryos may undergo permanent arrest during preimplantation development, fail to implant or spontaneously abort. Most aneuploidies originate during female meiosis and become increasingly common with advancing maternal age. To shed further light on the nature of aneuploidy in human oocytes, we utilized comparative genomic hybridization (CGH) to provide a detailed cytogenetic analysis of 308 first and second polar bodies (PBs). These were biopsied from fertilized oocytes, generated by 70 reproductively older women (average maternal age of 40.8 years). The total oocyte abnormality rate was 70%, and MII anomalies predominated over MI (50% aneuploidy rate versus 40.3%). Both whole chromosome non-disjunction and unbalanced chromatid predivision were seen, but the latter was the dominant MI aneuploidy-causing mechanism. Chromosome losses occurred more frequently than chromosome gains, especially during MI. Chromosomes of all sizes were found to participate in aneuploidy events, although errors involving smaller chromosomes were more common. These data reveal the spectrum of aneuploidies arising after each meiotic division, indicating that oocyte-derived abnormalities present at conception differ from those observed in established pregnancies. It is also clear that advancing maternal age had a significant adverse effect on female meiosis, and that this effect is most pronounced in MII. Indeed, our data suggest that MII may be more susceptible to age-related errors than MI.


Asunto(s)
Aneuploidia , Cromátides/patología , Cromosomas Humanos , Meiosis , Cuerpos Polares/patología , Adulto , Cromátides/metabolismo , Hibridación Genómica Comparativa , Análisis Citogenético , Femenino , Fertilización In Vitro , Humanos , Masculino , Edad Materna , Persona de Mediana Edad , Cuerpos Polares/metabolismo , Embarazo
13.
Hum Reprod ; 26(2): 480-90, 2011 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-21147821

RESUMEN

BACKGROUND: Recent studies have suggested that biopsy of several trophectoderm (TE) cells from blastocysts followed by comparative genomic hybridization (CGH) analysis might represent an optimal strategy for aneuploidy detection, but few data on accuracy are available. The main question concerns the rate of mosaicism at the blastocyst stage, and to what extent this might cause misdiagnoses. We assessed blastocyst aneuploidy and mosaicism rates and evaluated the accuracy and efficiency of CGH and microarray-CGH (aCGH) for TE analysis. METHODS: A total of 52 blastocysts, from 20 couples, were biopsied and their chromosomes examined by CGH. The remaining cells were spread and tested by fluorescent in situ hybridization (FISH). Of the 52 blastocysts, 20 underwent a second TE biopsy and were tested using aCGH. RESULTS: CGH and aCGH produced results for 98% of TE samples. 42.3% of blastocysts were uniformly euploid, 30% were uniformly aneuploid and 32.4% were mosaic. Of the mosaic embryos, 15.4% were found to be composed of a mixture of different aneuploid cell lines, while 17% contained both normal and aneuploid cells. Mosaic diploid-aneuploid blastocysts with >30% normal cells accounted for <6% of analysed embryos. CONCLUSIONS: Comprehensive chromosome screening and follow-up assessment of large numbers of cells provided a unique insight into the cytogenetics of human blastocysts. Meiotic and post-zygotic errors leading to mosaicism were common. However, most mosaic blastocysts contained no normal cells. Hence, CGH or aCGH TE analysis is an accurate aneuploidy detection tool and may assist in identifying viable euploid embryos with higher implantation potential.


Asunto(s)
Aneuploidia , Blastocisto/citología , Hibridación Genómica Comparativa , Análisis Citogenético/métodos , Hibridación Fluorescente in Situ , Adulto , Aberraciones Cromosómicas , Femenino , Humanos , Análisis por Micromatrices , Mosaicismo , Análisis de Secuencia por Matrices de Oligonucleótidos , Embarazo
14.
Fertil Steril ; 95(2): 520-4, 2011 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-20537630

RESUMEN

OBJECTIVE: To assess correlation between blastocyst morphology and chromosomal status. DESIGN: Observational research study. SETTING: An IVF clinic and a specialist preimplanation genetic diagnosis (PGD) laboratory. PATIENT(S): Ninety-three couples undergoing IVF treatment in combination with chromosome screening of embryos. INTERVENTION(S): Five hundred blastocysts underwent trophectoderm biopsy and comprehensive chromosome screening using comparative genomic hybridization (CGH). The morphology of the embryos was evaluated using standard methods. MAIN OUTCOME MEASURE(S): Association of aneuploidy and morphologic score. RESULT(S): A total of 56.7% of blastocysts were aneuploid. One-half of the grade 5/6 blastocysts were euploid, compared with only 37.5% of embryos graded 1/2, suggesting an effect of aneuploidy on blastocyst development. Aneuploidy also had a negative effect on inner cell mass and trophectoderm grades. Morphologically poor blastocysts had a higher incidence of monosomy and abnormalities affecting several chromosomes. The gender ratio was significantly skewed in relation to morphology. A total of 72% of blastocysts attaining the highest morphologic scores (5AA and 6AA) were found to be male, compared with only 40% of grade 3 embryos. CONCLUSION(S): Morphology and aneuploidy are linked at the blastocyst stage. However, the association is weak, and consequently, morphologic analysis cannot be relied on to ensure transfer of chromosomally normal embryos. A significant proportion of aneuploid embryos are capable of achieving the highest morphologic scores, and some euploid embryos are of poor morphology. Gender was associated with blastocyst grading, male embryos developing at a significantly faster rate than females.


Asunto(s)
Blastocisto/citología , Aberraciones Cromosómicas , Embrión de Mamíferos/fisiología , Caracteres Sexuales , Adulto , Aneuploidia , Blastocisto/fisiología , Aberraciones Cromosómicas/embriología , Hibridación Genómica Comparativa , Embrión de Mamíferos/citología , Desarrollo Embrionario/genética , Desarrollo Embrionario/fisiología , Femenino , Fertilización In Vitro , Humanos , Masculino , Embarazo , Diagnóstico Preimplantación/métodos , Razón de Masculinidad
15.
Fertil Steril ; 94(3): 875-87, 2010 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-19540479

RESUMEN

OBJECTIVE: To identify and transfer cytogenetically normal embryos after screening all chromosomes of first and second polar bodies (PBs) or trophectoderm samples with the use of comparative genomic hybridization. DESIGN: Clinical research study. SETTING: In vitro fertilization clinic referring samples to a specialist preimplantation genetic diagnosis laboratory. PATIENT(S): Thirty-two couples with repeated implantation failure. INTERVENTION(S): Zygotes from patients with repeated implantation failure and poor response to ovarian stimulation underwent PB biopsy. Patients with repeated implantation failure who were candidates for blastocyst transfer received trophectoderm biopsy. Zygotes or blastocysts were vitrified while chromosome analysis took place. Euploid embryos were transferred during a subsequent cycle. MAIN OUTCOME MEASURE(S): Cytogenetic status and implantation and pregnancy rates. RESULT(S): The oocyte and blastocyst aneuploidy rates were 65.5% and 45.2%, respectively. Abnormalities affecting all chromosomes were detected. Implantation and pregnancy rates for the patients with PB biopsy were 11.5% and 21.4%, respectively, whereas for patients receiving blastocyst analysis they were 58.3% and 69.2%. CONCLUSION(S): Initial results for patients of advanced maternal age (39.8 years) with repeated implantation failure and poor ovarian response were encouraging. However, further study is required to confirm whether or not screening is beneficial. Blastocyst analysis was associated with high pregnancy rates, suggesting that comprehensive chromosome screening may assist patients with repeated implantation failure capable of producing blastocysts in achieving pregnancies.


Asunto(s)
Aborto Habitual/genética , Blastocisto/citología , Cromosomas Humanos , Pérdida del Embrión/genética , Aborto Habitual/diagnóstico , Adulto , Blastocisto/metabolismo , Células Cultivadas , Cromosomas Humanos/genética , Cromosomas Humanos/metabolismo , Hibridación Genómica Comparativa , Análisis Citogenético , Técnicas de Cultivo de Embriones , Implantación del Embrión/genética , Pérdida del Embrión/diagnóstico , Composición Familiar , Femenino , Humanos , Masculino , Embarazo , Índice de Embarazo , Diagnóstico Preimplantación/métodos
16.
Mol Hum Reprod ; 14(12): 703-10, 2008 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-18957518

RESUMEN

One of the most important factors influencing embryo viability is chromosome imbalance (aneuploidy). Embryos derived from aneuploid gametes have little potential for forming a viable pregnancy, but cannot be distinguished from normal embryos using standard morphological evaluation. For more than a decade, preimplantation genetic screening (PGS) has been used to assist in the identification of aneuploid embryos. However, current strategies, based upon cell biopsy followed by fluorescent in situhybridization, allow less than half of the chromosomes to be screened. In this review, we discuss methods that overcome the limitations of earlier PGS strategies and provide screening of the entire chromosome complement in oocytes and embryos. In recent months, there has been a rapid growth in the number of PGS cycles utilizing one such method, comparative genomic hybridization (CGH). Data from IVF cycles utilizing CGH must be considered preliminary, but appear to indicate a dramatic increase in embryo implantation following comprehensive chromosomal screening. It is expected that methods based upon microarrays will yield similar clinical results and may be sufficiently rapid to permit comprehensive screening without the need for embryo cryopreservation. Some microarray platforms also offer the advantage of embryo fingerprinting and the potential for combined aneuploidy and single gene disorder diagnosis. However, more data concerning accuracy and further reductions in the price of tests will be necessary before microarrays can be widely applied.


Asunto(s)
Aberraciones Cromosómicas , Hibridación Genómica Comparativa , Embrión de Mamíferos/fisiología , Pruebas Genéticas/métodos , Análisis por Micromatrices , Hibridación Genómica Comparativa/métodos , Hibridación Genómica Comparativa/estadística & datos numéricos , Femenino , Humanos , Hibridación Fluorescente in Situ , Análisis por Micromatrices/métodos , Análisis por Micromatrices/estadística & datos numéricos , Polimorfismo de Nucleótido Simple , Embarazo
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