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Researchers Find Possible Way to Choose 'Good' Eggs in IVF
a blog by Claire, June 1, 2012
Pardon the grammar, but genetics is where it's at.
Genetic advances continue in the field of reproductive medicine, offering hope for increased rates of successful fertility treatments. Comprehensive chromosomal screening (CCS), a type of preimplantation genetic screening (PGS), is one of these advances — a test in which a cell is extracted from the embryo for testing prior to the embryo transfer. Then the fertility doctor can select the embryos that are most likely to implant and continue on in a successful pregnancy and birth.
Now, researchers at Yale and the University of Oxford have published a study that may lead to a way to non-invasively test a woman's eggs — not embryos — to find out if they have chromosomal abnormalities. The scientists have identified a set of genes that are less active in cells associated with abnormal eggs. The expression of two genes — SPSB2 and TP5313 — was consistently underrepresented in cumulus cells that surrounded abnormal eggs, while these same genes were normally expressed in eggs with the correct number of chromosomes.
During an in vitro fertilization (IVF) cycle, only a few eggs are usually able to produce a pregnancy because many eggs have the wrong number of chromosomes. If the egg is missing a chromosome or has an extra chromosome, it is called aneuploidy. Egg aneuploidy increases as a woman ages. This new discovery may allow fertility doctors to have a non-invasive test to select eggs without aneuploidy that can go on to be fertilized and create a successful pregnancy.
The results are published in the May 2012 issue of the journal Human Reproduction.
"This finding opens up the possibility of a safe, effective, and inexpensive way of identifying healthy eggs, potentially lowering the risks of miscarriage and Down syndrome," says Dagan Wells of the University of Oxford. "By conducting these tests before eggs are fertilized, ethical concerns about analysis of human embryos are avoided."