Embryos Correct for Genetic Abnormalities

by Dr. Susan Daniel

Early human embryos can contain both genetically normal and abnormal cells. They are said to exhibit mosaicism. At the recent meeting of the European Society for Human Reproduction and Embryology (ESHRE) in Stockholm, Sweden, Drs. William Kearns and Paul Brezina presented results of a study that indicates that embryos containing abnormal cells are capable of relegating those cells to the sidelines where they stop developing while the normal cells continue to grow.
by Dr. Susan Daniel

In the study, they re-examined embryos that had been determined to be abnormal after removal of a single cell on the third day after oocyte retrieval and insemination (day 3). The embryos were retested if they reached the blastocyst stage (days 5-6). The scientists found that 16/25 of the embryos diagnosed as abnormal on day 3 were genetically normal blastocysts. Based on these results, Drs. Kearns and Brezina concluded that it is probably common for human embryos to have both normal and abnormal cells in the early stages of development. By some as yet unknown mechanisms, some of these embryos are able to exclude the abnormal cells while promoting the development of the normal ones.

“Early embryos can correct genetic abnormalities during development: findings have significant implications for fertility treatment and stem cell therapies”. 5 July 2011. http://www.ivf.net/ivf/early-embryos-can-correct-genetic-abnormalities-during-development-findings-have-significant-implications-for-fertility-treatment-and-stem-cell-therapies-o6051.html