U.S. and U.K. researchers say they identified the chromosomal makeup of a human egg that may make it possible to avoid abnormal eggs in in vitro fertilization.
Dr. Pasquale Patrizio, director of the Yale Fertility Center director, and Dagan Wells of the University of Oxford in England, said the discovery might soon allow them to avoid using abnormal -- or aneuploid -- eggs during infertility treatments.
It would allow for the picking of eggs that are healthy enough for a successful in vitro fertilization cycle, the researchers said.
Only a few oocytes -- 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, this is referred to as aneuploidy. This problem increases as women age, Patrizio said.
Oocytes are surrounded by cumulus cells, which regulate and assist the process of egg maturation.
In this study, Patrizio and Wells of the University 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.
The study, published in the journal Human Reproduction, found two genes -- 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.