PGT-A

PGT-A (Preimplantation Genetic Testing for Aneuploidy), formerly referred to as PGS (Preimplantation Genetic Screening) determines the chromosomal status of an embryo by screening all 23 chromosome pairs prior to transfer in an IVF cycle.

Extensively validated

The VeriSeq PGS solution was extensively validated during in a large pre-clinical, multisite study. The product was validated for the detection of aneuploidy in preimplantation embryos, with both cell lines and embryo biopsy samples. The data set contained a good representation of chromosome losses and gains across all chromosomes which ensure a thorough evaluation of assay performance. VeriSeq PGS reliably detected chromosome aneuploidies in low DNA input samples across multiple sites, whether from biopsy of a single cell or a few cells.

Peer-Reviewed Publication

Fiorentino et al., (2014)10 performed a validation of the VeriSeq PGS Solution to investigate its applicability to PGT-A. Karyotypically defined chromosomally abnormal single cells and whole-genome amplified products, previously analysed by array-CGH, selected from 68 clinical PGT-A cycles with embryos biopsied at cleavage stage. NGS specificity for aneuploid embryo call was 100% with a sensitivity of 100%. Fiorentino concluded that this product demonstrated a robust methodology ready for clinical applications in reproductive medicine, which potential advantages of reduced costs and enhanced precision.

PGT-A and mosaicism - the good, the bad and the ugly

This blog post takes you through the basics, the history, the advantages, the debates and what is yet to be determined when it comes to preimplantation genetic testing in assisted reproduction.

PGT-M

Preimplantation genetic testing for Monogenic Disease (PGT-M) assesses embryos to help prevent the transmission of an inherited genetic disorder to children.

Improve outcomes by better embryo selection

Couples may know that they are a carrier of a genetic disorder because they already have an affected child or they may be aware of a family history of the disorders or may have had their DNA tested. For these couples there is a chance that they could have a child who is affected by this genetic disorder. Using Preimplantation Genetic Testing for Monogenic Disorders (PGT-M) it is possible to avoid passing on that genetic disorders to their offspring. The technique works by screening the embryos for the disorders before implantation in the womb. In order to carry out PGT-M, in vitro fertilisation is essential so that several embryos can be produced and tested to find out which ones are suitable for transfer.

Karyomapping: A comprehensive genome-wide test for PGT-M

A blood samples is taken from the father, the mother and a close relative of known disease status (called reference). The technique of Karyomapping looks at the chromosomes of the mother, father and the reference at approximately 300,000 different points and finds a DNA fingerprint unique to the chromosome that carries the defective gene. Using IVF, embryos are tested to reveal those that have inherited the affected chromosome and those that have inherited normal copies of the gene and likely to be free of the disorder. Embryo that are considered free of the disorder are transfer to the mother’s uterus.

Karyomapping is highly accurate

Natesan et al., (2014) reported the validation of karyomapping in a multi-centre study in which parental, reference and 2018 embryos samples from 44 PGT-M cases were genotyped retrospectively for ~300,000 genome-wide SNP loci. Each sample was karyomapped, the disease status was analysed blind and the results were compared for concordance with the original diagnosis based on targeted haplotyping with direct mutation detection. The result showed that karyomapping is highly accurate and facilitate the inheritance of almost any single-gene defect, greatly expanding the range of conditions that PGT-M can be offered clinical without the need for customised test development.

Karyomapping is a highly efficient, accurate and robust method for PGT-M of single gene disorders

Konstantinidis et al., (2015) reported their own validation results and the first prospective clinical application of karyomapping, ongoing pregnancies and live births in a series of single-gene defect cases. The results presented in the study indicated that karyomapping is a highly efficient, accurate and robust method for PGT-M of single gene disorders. In addition they confirm that the principle advantage of karyomapping is a significant reduction in the time and effort required to prepare for a PGT-M cycle, which for karyomapping only involves genotyping the parents and child or relative to confirm that is sufficient informative SNP coverage in a particular family and single-gene defect locus.