New Tests Spot Genetic Abnormalities in Early Development

Many early embryos, such as the one pictured here, possess genetic defects and are responsible for failed pregnancies. Researchers believe a new early development embryo test can improve success rates for infertile patients.

S A N D I E G O, Oct. 23   Most human embryos possess genetic defects just days into their development, a finding that researchers say may explain why many pregnancies fail shortly after conception.
　　 Researchers who studied all 46 chromosomes in 3-day-old embryos said Sunday they believe a new test can improve success rates for infertile patients by allowing doctors to choose embryos with normal sets of chromosomes for implantation into a mother’s womb.
　　 The technology could also decrease the number of multiple births to women undergoing in-vitro fertilization because less embryos would have to be inserted into the womb to lead to a successful pregnancy.
　　Culling Chromosomal Info
　　“This is a technique that allows an unprecedented amount of chromosomal information to be gained from looking at a single cell,"said Dagan Wells, one of the University College in London, researchers in charge of the study.
　　 The results indicate that uniform cell development often didn’t occur in the first few days after conception.
　　 Wells said cells instead would often divide unevenly, with chromosomes sticking together in destructive clusters or not dividing at all. Almost all human cells have 46 chromosomes, 23 from each parent.
　　 Wells and colleague Joy Delhanty studied 12 embryos at 3 days old. Only three contained complete sets of chromosomes. Abnormality occurred in nine of the embryos, including broken or hybrid sets of chromosomes. Three of the embryos had no normal cells at all, Wells said.
　　 He added that while the study reveals many embryos aren’t viable, the results shouldn’t be interpreted to mean that all embryos are flawed, as previous researchers had speculated using less sophisticated tests.

Self-Repair Embryos
　　“There have been cases where early tests have shown a chromosomal abnormality in an embryo, but when the baby is born, it doesn’t have the abnormality,"Wells said. “So, theories suggest it is possible for the embryos to fix themselves in some cases."br /> 　　 Wells is doing research at the Institute for Reproductive Medicine and Science in West Orange, N.J., to improve the testing process.
　　 The process is not ready for clinical trial because the time it takes to complete the procedure exceeds six days "the maximum time fertility doctors will keep an embryo outside the womb.
　　 The findings were presented to reporters Sunday at the American Society for Reproductive Medicine’s annual meeting in San Diego.

(From ABCnews)