Twelve years of assessing the quality of preimplantation genetic testing for monogenic disorders.

Objective: Genomics Quality Assessment has provided external quality assessments (EQAs) for preimplantation genetic testing (PGT) for 12 years for eight monogenic diseases to identify sub-optimal PGT strategies, testing and reporting of results, which can be shared with the genomics community to aid optimised standards of PGT services for couples.

Method: The EQAs were provided in two stages to mimic end-to-end protocols. Stage 1 involved DNA feasibility testing of a couple undergoing PGT and affected proband.

Development and clinical application of a preimplantation genetic testing for monogenic disease (PGT-M) for beta thalassemia in Vietnam.

Purpose: The purpose of this research is to study the clinical outcomes using a next-generation sequencing-based protocol allowing for simultaneous testing of mutations in the beta thalassemia (HBB) gene, including single nucleotide polymorphism (SNP) markers for PGT-M along with low-pass whole genome analysis of chromosome aneuploidies for PGT-A.

Methods: A combined PGT-M (thalassemia) plus PGT-A system was developed for patients undergoing IVF in Vietnam. Here we developed a system for testing numerous thalassemia mutations plus SNP-based testing for backup mutation analysis and contamination control using next-generation sequencing (NGS).

Aneuploidy Screening using Next Generation Sequencing.

Chromosomal aneuploidy is recognized to be a significant contributing factor in implantation failure and spontaneous miscarriage Hellani et al. (Reprod Biomed Online 17:841-847, 2008), Vanneste et al. (Nat Med 15:577-583, 2009) and is likely to be responsible for the majority of IVF failure [Baltaci et al.

Current experience concerning mosaic embryos diagnosed during preimplantation genetic screening.

The concept of embryos containing multiple cell lines (mosaicism) is not new, but much attention has been paid to this concept recently owing to recent advances in molecular techniques to analyze human embryos. Mosaicism in embryos has been known and reported for some time, originally in early cleavage-stage embryos diagnosed with the use of fluorescence in situ hybridization (FISH). However, the early data have come under attack owing to the limited ability of FISH to reliably detect the actual copy number count of chromosomes as well as potential ascertainment bias of those early studies, which were all performed on already analyzed embryos found to be aneuploid.

The improvement of the best practice guidelines for preimplantation genetic diagnosis of cystic fibrosis: toward an international consensus.

Cystic fibrosis (CF) is one of the most common indications for preimplantation genetic diagnosis (PGD) for single gene disorders, giving couples the opportunity to conceive unaffected children without having to consider termination of pregnancy. However, there are no available standardized protocols, so that each center has to develop its own diagnostic strategies and procedures. Furthermore, reproductive decisions are complicated by the diversity of disease-causing variants in the CFTR (cystic fibrosis transmembrane conductance regulator) gene and the complexity of correlations between genotypes and associated phenotypes, so that attitudes and practices toward the risks for future offspring can vary greatly between countries.

Current issues in medically assisted reproduction and genetics in Europe: research, clinical practice, ethics, legal issues and policy.

Study Question: How has the interface between genetics and assisted reproduction technology (ART) evolved since 2005?

Summary Answer: The interface between ART and genetics has become more entwined as we increase our understanding about the genetics of infertility and we are able to perform more comprehensive genetic testing.

What Is Known Already: In March 2005, a group of experts from the European Society of Human Genetics and European Society of Human Reproduction and Embryology met to discuss the interface between genetics and ART and published an extended background paper, recommendations and two Editorials.

Study Design, Size, Duration: An interdisciplinary workshop was held, involving representatives of both professional societies and experts from the European Union Eurogentest2 Coordination Action Project.

Evaluation of PCR-based preimplantation genetic diagnosis applied to monogenic diseases: a collaborative ESHRE PGD consortium study.

Preimplantation genetic diagnosis (PGD) for monogenic disorders currently involves polymerase chain reaction (PCR)-based methods, which must be robust, sensitive and highly accurate, precluding misdiagnosis. Twelve adverse misdiagnoses reported to the ESHRE PGD-Consortium are likely an underestimate. This retrospective study, involving six PGD centres, assessed the validity of PCR-based PGD through reanalysis of untransferred embryos from monogenic-PGD cycles.

Current issues in medically assisted reproduction and genetics in Europe: research, clinical practice, ethics, legal issues and policy. European Society of Human Genetics and European Society of Human Reproduction and Embryology.

In March 2005, a group of experts from the European Society of Human Genetics and European Society of Human Reproduction and Embryology met to discuss the interface between genetics and assisted reproductive technology (ART), and published an extended background paper, recommendations and two Editorials. Seven years later, in March 2012, a follow-up interdisciplinary workshop was held, involving representatives of both professional societies, including experts from the European Union Eurogentest2 Coordination Action Project. The main goal of this meeting was to discuss developments at the interface between clinical genetics and ARTs.

Diminished effect of maternal age on implantation after preimplantation genetic diagnosis with array comparative genomic hybridization.

Objective: To assess the relationship between maternal age, chromosome abnormality, implantation, and pregnancy loss.

Design: Multicenter retrospective study.

Setting: IVF centers in the United States.

The experience of 3 years of external quality assessment of preimplantation genetic diagnosis for cystic fibrosis.

Preimplantation genetic diagnosis (PGD) was first performed over 20 years ago and has become an accepted part of genetic testing and assisted reproduction worldwide. The techniques and protocols necessary to carry out genetic testing at the single-cell level can be difficult to master and have been developed independently by the laboratories worldwide offering preimplantation testing. These factors indicated the need for an external quality assessment (EQA) scheme for monogenic disease PGD.

Chromosomal disorders and male infertility.

Infertility in humans is surprisingly common occurring in approximately 15% of the population wishing to start a family. Despite this, the molecular and genetic factors underlying the cause of infertility remain largely undiscovered. Nevertheless, more and more genetic factors associated with infertility are being identified.

The use of arrays in preimplantation genetic diagnosis and screening.

Background: In preimplantation genetic diagnosis (PGD), polymerase chain reaction has been used to detect monogenic disorders, and in PGD/preimplantation genetic screening (PGS), fluorescence in situ hybridization (FISH) has been used to analyze chromosomes. Ten randomized controlled trials (RCTs) using FISH-based PGS on cleavage-stage embryos and one on blastocyst-stage embryos have shown that PGS does not increase delivery rates. Is the failure of PGS due to a fundamental flaw in the idea, or are the techniques that are being used unable to overcome their own, inherent flaws? Array-based technology allows for analysis of all of the chromosomes.

Polymerase chain reaction-based detection of chromosomal imbalances on embryos: the evolution of preimplantation genetic diagnosis for chromosomal translocations.

Objective: To develop and assess a polymerase chain reaction (PCR)-based preimplantation genetic diagnosis (PGD) approach for detection of chromosomal imbalances in embryos.

Design: A prospective study of embryos derived from chromosome translocation carriers that have undergone PGD using a novel molecular-based approach.

Setting: A reference molecular genetics laboratory specialized in the provision of transport PGD services and a private IVF clinic.

What next for preimplantation genetic screening (PGS)? A position statement from the ESHRE PGD Consortium Steering Committee.

Since 2004, there have been 11 randomized controlled trials (RCTs) mainly for advanced maternal age (AMA), which have shown no benefit of performing preimplantation genetic screening (PGS). Ten of the RCTs have been performed at the cleavage stage and one at the blastocyst stage. It is probable that the high levels of chromosomal mosaicism at cleavage stages, which may result in the tested cell not being representative of the embryo, and the inability to examine all of the chromosomes using fluorescence in situ hybridization, have contributed to the lack of positive outcome from the RCTs.

Karyomapping: a universal method for genome wide analysis of genetic disease based on mapping crossovers between parental haplotypes.

The use of genome wide single nucleotide polymorphism (SNP) arrays for high resolution molecular cytogenetic analysis using a combination of quantitative and genotype analysis is well established. This study demonstrates that by Mendelian analysis of the SNP genotypes of the parents and a sibling or other appropriate family member to establish phase, it is possible to identify informative loci for each of the four parental haplotypes across each chromosome and map the inheritance of these haplotypes and the position of any crossovers in the proband. The resulting 'karyomap', unlike a karyotype, identifies the parental and grandparental origin of each chromosome and chromosome segment and is unique for every individual being defined by the independent segregation of parental chromosomes and the pattern of non-recombinant and recombinant chromosomes.

What next for preimplantation genetic screening?

Preimplantation genetic diagnosis for aneuploidy screening (preimplantation genetic screening-PGS) has been used to detect chromosomally normal embryos from subfertile patients. The main indications are advanced maternal age (AMA), repeated implantation failure, repeated miscarriages and severe male factor infertility. Many non-randomized PGS studies have been published and report an increase in implantation rate, and/or a decrease in miscarriage rate.

Non-disclosing preimplantation genetic diagnosis for Huntington disease.

Objectives: Individuals at risk for Huntington disease face difficult decisions regarding their reproductive options. Most do not wish to pass on the gene for Huntington disease to their children, but may not be prepared themselves to undergo presymptomatic testing and learn their genetic status. For these reasons, many at-risk individuals with a family history of HD would choose a method of genetic diagnosis that would assure them that they can have children unaffected with HD without revealing their own genetic status (non-disclosing).