A new discovery by researchers at Yale and the University of Oxford may allow medicos to avoid using aneuploid (abnormal) eggs during infertility treatments. The results appear in the journal Human Reproduction.
Generally, only a few eggs per IVF treatment cycle are 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 referred to as "aneuploidy." This problem increases as women grow older.
Yale scientist Pasquale Patrizio explained that eggs are surrounded by cells, known as cumulus cells, which regulate and assist the process of egg maturation. Patrizio and Dagan Wells of Oxford studied genes expressed in the cumulus cells and were able to identify a set of genes that are less active in cells that are associated with abnormal eggs.
They characterized two genes - known as SPSB2 and TP5313 - and found that the expression of these genes 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.
"The identification of these genes in cumulus cells can serve as a novel, non-invasive marker to identify abnormal oocytes and thus ultimately improve IVF success rates," said Patrizio. "We can use cumulus cells surrounding the eggs to gain insight into the health of an egg. These cells are now able to inform us about the chromosomal makeup of an egg. This can help us know if it is the 'right egg.'" Wells added that by conducting these tests before eggs are fertilized, ethical concerns about analysis of human embryos are avoided.
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Source: Yale University