Identification of Abnormal Oocyte Should Improve IVF Success Rates

Scientists have identified the chromosomal make-up of a human egg. This discovery should allow them to avoid using abnormal eggs during infertility treatments, and instead to pick eggs that are healthy enough for a successful in vitro fertilization (IVF) cycle.

Only a few oocytes per IVF treatment cycle are able to produce a pregnancy because many eggs have the wrong number of chromosomes. The problem increases as women age.

Oocytes are surrounded by cumulus cells, which regulate and assist the process of egg maturation. In this study, Yale Fertility Center (New Haven, CT, USA) director Dr. Pasquale Patrizio, and Dagan Wells of the University of Oxford (Oxford, United Kingdom) studied genes expressed in the cumulus cells. They were able to identify a set of genes that are less active in cells that are associated with abnormal eggs.

They 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.

"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 Dr. Wells. "By conducting these tests before eggs are fertilized, ethical concerns about analysis of human embryos are avoided."

The study is published in the May 2012 issue of the journal Human Reproduction.

Related Links:
Yale Fertility Center
University of Oxford