New method for choosing `right` eggs in IVF to boost success rates

A team of researchers have identified the chromosomal make-up of a human egg, which may soon help them to pick healthy eggs, and avoid abnormal ones to up the rates of successful in vitro fertilization (IVF), cycle. Only a few Oocytes (eggs) per IVF treatment cycle are able to result in pregnancy because many eggs have the wrong number of chromosomes. If the egg is missing a chromosome or has an extra chromosome, it is an abnormal or aneuploid egg. This condition is referred to as aneuploidy and the problem only gets worse as women age. Cells, known as cumulus cells surround oocytes. Cumulus cells regulate and assist the process of egg maturation. In this study, Yale Fertility Center director Pasquale Patrizio, M. D., and Dagan Wells of the University of Oxford analysed genes expressed in the cumulus cells. They were able to recognize a set of genes that are less active in cells that are associated with abnormal eggs. The researchers characterized 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. "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, professor in the Department of Obstetrics, Gynecology & Reproductive Sciences at Yale. "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'' to be fertilized and produce a baby," he said. "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," said Wells. "By conducting these tests before eggs are fertilized, ethical concerns about analysis of human embryos are avoided," he added. This study has been published in the journal Human Reproduction.