Preimplantation Genetic Testing for Chromosomal Abnormalities: Aneuploidy, Mosaicism, and Structural Rearrangements

Meiotic Behaviour of Chromosomes Involved in Structural Chromosomal Abnormalities Determined by Preimplantation Genetic Diagnosis

Aneuploidy and Confined Chromosomal Mosaicism in the Developing Human Brain

BACKGROUND Understanding the mechanisms underlying generation of neuronal variability and complexity remains the central challenge for neuroscience. Structural variation in the neuronal genome is likely to be one important mechanism for neuronal diversity and brain diseases. Large-scale genomic variations due to loss or gain of whole chromosomes (aneuploidy) have been described in cells of the ...

Preimplantation genetic diagnosis of numerical and structural chromosome abnormalities.

The causes of the decline in implantation rates observed with increasing maternal age are still a matter for debate. Data from oocyte donation strongly suggest that in women of advanced reproductive age, the ability to become pregnant is largely unaffected while oocyte quality is compromised. The incidence of chromosomal abnormalities in embryos is considerably higher than that reported in spon...

Preimplantation Genetic Diagnosis (PGD) for chromosome rearrangements

• Chromosome rearrangements include Robertsonian and reciprocal translocations (the most common form of chromosome abnormality in humans, present in approximately 1 in 500 individuals), periand paracentric inversions, interand intra-chromosomal insertions, deletions, duplications, and complex chromosome rearrangements (CCRs). • In all cases presenting for PGD, the risk of viable abnormality sho...

What next for preimplantation genetic screening (PGS)? Experience with blastocyst biopsy and testing for aneuploidy.

Blastocysts more commonly have a normal karyotype than cleavage-stage embryos do. Moreover, blastocysts have also made a metabolic transition from catabolism and recycling of the oocyte's reserves and resources, processes that fuel the first 3 days of cleavage. Although not all blastocysts are karyotypically equal, it is still to be determined to what extent a mosaic karyotype might be a normal...