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).

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.

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.

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.

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.

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).