ART in recurrent miscarriage: preimplantation genetic diagnosis/screening or surrogacy?

Recently, assisted reproductive techniques have been used to prevent further miscarriages in women with recurrent miscarriage. One approach uses either screening or diagnosis of embryonic chromosomes prior to embryo replacement [preimplantation genetic screening (PGS)/preimplantation genetic diagnosis (PGD)]. The second approach involves surrogacy. However, PGS/PGD assumes that the embryo is chromosomally abnormal, and that the mother should receive a chromosomally normal embryo. Surrogacy assumes that the embryo is normal and that the maternal environment needs to be substituted. This article examines the place of both techniques in different types of recurrent miscarriage, and tries to give guidelines as to which technique is preferable depending on the likelihood of an embryonic chromosome aberration. In repeated fetal aneuploidy or in the older patient, PGS or PGD are preferable. However, with high numbers of miscarriages, or in autoimmune pregnancy loss, surrogacy is preferable. In the light of recent work, it is uncertain which treatment mode is indicated in balanced parental chromosome aberrations. In conclusion, both techniques have a place, but probably only in those patients with a poor prognosis in whom assisted reproductive techniques will be shown to improve the subsequent live birth rate above the spontaneous rate.     

Comparison of the results of human embryo biopsy and outcome of PGD after zona drilling using acid Tyrode medium or a laser

BACKGROUND: Zona pellucida opening for blastomere removal can be done by mechanical or chemical means, or by laser. So far, only limited data on the use of laser systems for zona drilling in cases of PGD are available. METHODS: Results of embryo biopsy and outcome of PGD in two periods were compared. In the first period, acid Tyrode medium was used for zona drilling. In the second period, zona drilling was performed by a 1.48 micro m infrared laser. RESULTS: In the first period, 59 cycles resulted in 53 biopsy procedures with 356 biopsied embryos. In the second period, these numbers were 69 cycles, 69 biopsy procedures and 402 biopsied embryos. Fewer blastomeres were intact (95.2%) after zona drilling with acid Tyrode than after laser zona drilling (98.3%, P = 0.02). Rates of positive HCG (37.5% versus 35.5%), ongoing pregnancy rates (31.3% versus 25.0%) and ongoing implantation rates (18.9% versus 14.9%) did not differ. CONCLUSIONS: The use of a laser for zona drilling in cases of PGD is an easier procedure and results in more intact blastomeres. Since similar pregnancy rates are obtained, it is advantageous to use a laser for zona drilling. Further follow-up is necessary to prove the safety of this procedure.     

Ethical issues in new uses of preimplantation genetic diagnosis: should parents be allowed to use preimplantation genetic diagnosis to choose the sexual orientation of their children?

Extending the application of preimplantation genetic diagnosis (PGD) to screen embryos for non-medical traits such as gender, height and intelligence, raises serious moral, legal, and social issues. In this paper I consider the possibility of using PGD to select the sexual orientation of offspring. After considering five potential objections, I conclude that parents should be permitted to use PGD to choose the sexual orientation of their children.     

Is Gender Selection an Appropriate Use of Medical Resources?

Gender selection by PGD is an appropriate use of medical resources. Children borne through PGD for gender determination would be welcome and would come into a couple's life at a planned, opportune time. If the practice were made more available through insurance coverage, the size and makeup of families could become a matter of choice rather than chance for couples favoring this approach.     

胚胎植入前遗传学诊断10个周期的临床分析

目的:初步探讨使用荧光原位杂交(FISH)方法对染色体异常患者进行胚胎植入前遗传学诊断(PGD)的临床意义。方法:7对不孕夫妇采用长方案控制性超排和卵胞浆内单精子注射,受精后d3胚胎活检、卵裂球固定和FISH,d4或d5择合适胚胎移植。结果:7对夫妇共进行10个PGD周期。获卵251个,可供活检胚胎133个,活检卵裂球207个,胚胎活检成功率为96.2%(128/133)。128个成功活检胚胎的197个卵裂球,其单细胞固定率为93.9%(185/197),FISH信号率为90.8%(168/185)。10个周期共移植22个胚胎,3例获得妊娠,并均足月分娩健康婴儿,其中1例孕妇平衡易位携带者于孕中期时,羊水核型分析为平衡易位携带者。结论:应用FISH方法进行PGD,是遗传病高危夫妇预防流产和染色体异常患儿出生的有效手段。     

Massively parallel sequencing on human cleavage-stage embryos to detect chromosomal abnormality

Purpose

Next-generation sequencing technology like MPS has recently been introduced to perform comprehensive chromosome screening on human trophectoderm samples for preimplantation embryo assessment. However, the potential of MPS in chromosome analysis of single cell from blastomeres has not yet been investigated.

Preimplantation genetic diagnosis for mitochondrial DNA disorders: ethical guidance for clinical practice

Although morally acceptable in theory, preimplantation genetic diagnosis (PGD) for mitochondrial DNA (mtDNA) disorders raises several ethical questions in clinical practice. This paper discusses the major conditions for good clinical practice. Our starting point is that PGD for mtDNA mutations should as far as possible be embedded in a scientific research protocol. For every clinical application of PGD for mtDNA disorders, it is not only important to avoid a ‘high risk of serious harm'' to the future child, but also to consider to what extent it would be possible, desirable and proportional to try to reduce the health risks and minimize harm. The first issue we discuss is oocyte sampling, which may point out whether PGD is feasible for a specific couple. The second issue is whether one blastomere represents the genetic composition of the embryo as a whole – and how this could (or should) be investigated. The third issue regards the cutoff points below which embryos are considered to be eligible for transfer. We scrutinize how to determine these cutoff points and how to use these cutoff points in clinical practice – for example, when parents ask to take more or less risks. The fourth issue regards the number of cycles that can (or should) justifiably be carried out to find the best possible embryo. Fifth, we discuss whether follow-up studies should be conducted, particularly the genetic testing of children born after IVF/PGD. Finally, we offer the main information that is required to obtain a truly informed consent.     

Preimplantation genetic diagnosis using combined strategies on a breast cancer patient with a novel genomic deletion in BRCA2

Purpose

To perform Preimplantation Genetic Diagnosis (PGD) on a paternal Brca2 unknown mutation carrier with early-onset breast cancer, whose paternal grandmother and mother had breast cancer at 60s.

Method

Elucidating the linkage via single sperm haplotyping on patient''s carrier brother, and identifying the genomic deletion via BLAST followed by PCR screening. PGD was subsequently conducted.

Result

The mutant allele was found by using 4 microsatellite and 2 intragenic SNP markers. Recombination was detected in 8 % of sperms. BLAST was utilized to locate putative hairpin structure(s), followed by PCR screening with seven sets of primers. A novel 2,596 bp deletion containing exon 15 ~ 16 was identified. Due to the severity of phenotype and the integrity of exon 11 encoding RAD51 binding domain, and the fact that the patient''s mother also had breast cancer at her 60s, we speculate a possible coexistence of maternal breast cancer risk allele(s). Embryo biopsy was performed on day 3. Unaffected morula and blastocyst were replaced on day 5, resulting in a singleton livebirth. A breast lump appeared in the patient after delivery without the presence of malignant cells.

Conclusion

Concerning the assisted reproductive option for breast cancer patients, the possibility of coexistence of multiple familial risk alleles and the significance of each mutation to the phenotype should be evaluated. To eliminate misdiagnosis resulting from recombination and/or allelic drop-out, both direct mutation detection and linkage analysis approaches may be necessary. BLAST is a very useful and cost-effective tool for identifying large genomic deletion.     

Taskforce 9: the application of preimplantation genetic diagnosis for human leukocyte antigen typing of embryos

This 9th statement of the ESHRE Taskforce on Ethics and Law considers ethical questions and specific dilemmas concerning preimplantation genetic diagnosis for human leukocyte antigen typing of embryos. This application is particularly complex because the interests of the sick child needing a transplantation should be balanced against the interests of the future donor child who may result from the technique. It is concluded that, if parents intend to love the child, the creation and use as a donor is not inherently disrespectful.