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Breakthrough in Genetic Screening Combines Two Important Tests
March 4, 2013
Research findings presented at the American Society for Reproductive medicine’s annual conference in October 2012 say a breakthrough method of genetic screening combines two important tests for examining DNA and number of chromosomes in an embryo during an in vitro fertilization (IVF) cycle.
Using a microarray, or template for measuring normal chromosomes, scientists from the University of Oxford discovered that they were able to measure sequences of DNA (telomeres) and check for the correct number of chromosomes all in one test. Previously these measures were calculated separately.
Only the most genetically normal embryos are selected in genetic screening which reduces the risk of miscarriage. Nearly 60% of miscarriages are the result of chromosomal abnormalities that often go undetected unless the fertility patient opts for genetic testing.
The research team examined 37 polar bodies, 64 blastomeres and 16 trophectoderm biopsies of blastocysts during IVF cycles. They were able to detect that an embryo had an abnormal number of chromosomes in 226 of 240 cases and discovered that the incorrect number of chromosomes indicated shorter telomeres as well.
It is believed that this microarray model will allow for single embryo transfers (SET) during IVF. Fertility doctors strive to transfer just one genetically normal embryo in an IVF cycle, yielding high implantation and live birth rates.
These findings must be brought to clinical trial in order to test the efficacy at predicting implantation and live birth success rates. This study only examined how to best select genetically normal embryos, but did not collect data post-embryo transfer. Factors including uterine receptivity, health of the mother, and age of the mother at time of pregnancy can impact the rate of live birth.