Researchers Develop New Procedure to Screen All 46 Human Chromosomes to Identify Abnormalities in Embryos
New technology developed by researchers at Reproductive Medicine Associates
of New Jersey awarded General Program Prize Paper at American Society for
Reproductive Medicine Annual Meeting
WASHINGTON and MORRISTOWN, N.J., Oct. 18 /PRNewswire/ -- Researchers at Reproductive Medicine Associates of New Jersey (RMA) received the highest award for research at the American Society for Reproductive Medicine (ASRM) for developing a novel technology making it possible to provide accurate, rapid analysis of all 46 human chromosomes from a single cell taken from a human embryo. The ASRM Prize Paper Award is awarded to the most significant research in the field of human reproduction each year. This new technology makes it possible for the first time to fully evaluate the genetic make up of human embryos in a time frame which allows clinicians and scientists to use that information to help improve pregnancy rates, reduce miscarriage risk, and decrease the risk of some major congenital anomalies such as Down syndrome. This procedure, known as "Accurate 23 chromosome aneuploidy screening in human blastomeres using single nucleotide polymorphisms (SNP)," provides fertility specialists for the first time with a rapid and accurate technique to assess the genetic normality of human embryos created through in vitro fertilization (IVF). The results of this research effort were presented this week at the American Society for Reproductive Medicine (ASRM) meeting and were awarded the General Program Prize Paper Award, the highest award provided by this international professional society. Nathan Treff, Ph.D., lead author on the study and a researcher in molecular genetics at RMA, delivered the results in an oral presentation. "Accurate and rapid identification of chromosomally- abnormal (aneuploid) embryos within hours after embryo biopsy will provide physicians with the ability to select embryos for transfer to the uterus based on a far more complete and accurate picture of their genetic health than has ever been possible," said Dr. Treff. "This could, in turn, allow us to reduce the number of embryos implanted while increasing the chances that couples treated with IVF will have a healthy baby." It has been known for more than a decade that the principal reason human embryos fail to implant relates to the embryo having too much or too little genetic material. One example is Down syndrome where the embryo contains an extra chromosome 21. While that error is commonly known, the addition or loss of other chromosomes also occurs frequently, but those embryos generally arrest prior to implantation or result in early miscarriage. Unfortunately, genetically normal and abnormal embryos typically appear the same during the first few days of development. This means that embryologists and physicians cannot observe a given group of embryos and distinguish which are normal and have an excellent chance of implanting and developing into a healthy child from those which are abnormal and do not possess significant reproductive potential. A specific genetic screening test of each embryo is required. Currently, the most commonly used technology for chromosomal analysis of embryos (sometimes termed preimplantation genetic diagnosis or PGD), is florescent in situ hybridization (FISH). This technique assesses fewer than half of the 23 chromosome pairs found in the human karyotype and has a suboptimal error rate. This makes it possible for many genetic abnormalities to go undetected. Prior technologies that have attempted to analyze all 23 chromosome pairs have not been useful because of the length of time required to provide accurate results. "This groundbreaking research paves the way for more successful IVF treatments," says Dr. Richard T. Scott, founding partner of RMA. "Human embryos must implant within the first few days in order to achieve a pregnancy. This new technology developed at RMA combines for the first time both high accuracy and efficiency in embryonic chromosomal analysis with rapid assessment in a clinically-useful time frame." In this new process, a single cell is removed from an embryo on the third day of embryonic development. The 3 billion base-pairs of nucleic acid that make up a single copy of human DNA weigh only 6 trillionths of a gram, which is too small to allow analysis. It is necessary first to copy this code over one million times with great fidelity to accumulate sufficient DNA to accurately analyze the number of chromosomes present in the cell. This step, termed whole genomic amplification (WGA), one of many technologically demanding steps required for this process, has been refined extensively by the team at RMA. Once amplified, approximately 250,000 different areas of the DNA, called single nucleotide polymorphisms (SNPs, or "snips") are individually examined and assigned a specific copy number. These copy numbers are then collated for each chromosome and the number of each individual chromosome calculated. This process makes it possible to identify any deviation from the normal copy number of two for each chromosome pair in a developing embryo. Copy numbers of "one" or "three or more" indicate a chromosomally-abnormal embryo which would generally not implant but which may implant and lead to subsequent miscarriage or, rarely, result in the birth of an anomalous child. This technology should improve delivery rates of healthy children for some couples who are infertile or who experience recurrent miscarriage. About RMA Reproductive Medicine Associates (RMA) of New Jersey is one of the world's leading centers for treatment and research in reproductive medicine. RMA's founding partners and physicians have helped bring more than 17,000 babies to loving parents. RMA is also world-renowned for having one of the highest success rates in the treatment of infertility.
SOURCE Reproductive Medicine Associates of New Jersey
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