From Medicineworld.org: Genetic Testing Still Smart Choice
Cancer blog: I manage the cancer blog with lots of help and support form other bloggers. Through this cancer blog my friends and I try to bring stories of hope for patients with cancer. The cancer blog often republishes important blog posts from other cancer related blogs at Medicineworld.org. If you are searching for a blog that covers wide variety of cancer topics, this may be the one for you.
Breast cancer blog: Breast cancer blog is run by Emily and other bloggers and they bring you the latest stories, news and events that are related to breast cancer. Increasing awareness about breast cancer among women and in the general population is the main goal of this breast cancer blog.
Lung cancer blog: Lung cancer blog is managed by Scott with the help of other bloggers. Through this blog Scott and his friends constantly remind the readers about the dangers of smoking. It's a never-ending struggle against this miserable disease with which a social stigma of smoking is associated.
Colon cancer blog: Colon cancer blog is run by Sue and other bloggers. Sue brings a personal touch to the colon cancer blog since her mother died of colon cancer few years ago. She writes about stories, research news and advances in treatment related to colon cancer.
Prostate cancer blog: Prostate cancer is the most common cancer among American men. American Cancer Society estimates that over 230,000 new cases of prostate cancer occur in the United state every year. This important blog about prostate cancer is run by Mark and other bloggers. This blog brings news, stories, and other personal observations related to prostate cancer.
Medicineworld.org publishes a diabetes watch blog and this blog is run by JoAnn other bloggers. This diabetes watch blog brings you the latest in the field of diabetes. This includes personal stories, advances in diagnosis and treatment, and other observations about diabetes. Improving awareness about diabetes is an important mission of this group.
Genetic Testing Still Smart Choice
Citing concerns about the accuracy of preimplantation genetic diagnosis, the method a number of practitioners use to pick the healthiest embryos during IVF, UF scientists set out to study the procedure. Their work, described during a recent meeting of the American Society of Reproductive Medicine, reveals the technique is actually highly reliable. But because there is a slim chance a genetic abnormality can cause doctors to misdiagnose embryos, some concerns still need to be addressed, the scientists said.
Preimplantation genetic diagnosis has been used for more than a decade to screen embryos for hereditary diseases such as Down syndrome and other abnormalities. To do this, one cell from an eight-cell embryo is extracted and examined for chromosomal defects.
However, as a number of as half these embryos spawn cells with different genetic information as they divide, giving doctors an inaccurate idea of how the embryo will continue to develop, said Larissa Kovalinskaia, a UF research associate with the College of Medicine's IVF program. While a number of embryos with this abnormality - called chromosomal mosaicism - stop developing early, some go on to be born. Because these embryos' cells contain different sets of chromosomes, doctors cannot always accurately screen them for genetic diseases, Kovalinskaia said.
"As more data were coming out, saying that as a number of as 50 percent of (IVF) embryos were mosaic, we started worrying about the accuracy of preimplantation genetic diagnosis," she said. "When you take one cell, does it represent the entire embryo? What we've shown is that we can rely on PGD".
UF scientists estimate less than 3 percent of healthy embryos are discarded as abnormal and only 1.5 percent are implanted with undetected genetic defects because of mosaicism.
To find out how big of a problem mosaicism is, the scientists developed a mathematical model using data from UF's IVF program and other programs to illustrate the different paths an embryo takes as it develops. While half of embryos turn out normal, with no mosaicism, the other half produce irregular cells as they divide.
Embryos that become mosaic after their cells divide twice typically stop progressing by the time they have accumulated eight cells. Too a number of of their cells have chromosomes that don't match and these mixed messages lead the embryo to stop developing, Kovalinskaia said.
Embryos with only one or two irregular cells still have a chance to develop normally though, she said. These embryos tend to not develop this abnormality until after their cells have divided a third time, typically the time when doctors perform preimplantation genetic diagnosis. This is where the problem with diagnosis occurs, scientists say.
"Our pathway concept may help to explain the observed outcomes during preimplantation diagnosis," said Kenneth Drury, director of the UF IVF and Andrology Laboratory and a clinical professor in the College of Medicine who was one of the researchers. "When we biopsy an eight-cell embryo, if we choose (the one) normal cell in an abnormal embryo, we may believe that embryo is normal and transfer it.
"This occurs about 1 percent of the time, which means 99 percent of the time we will be accurate. Again the error is not due to a technical mistake but to natural errors occurring during early cell division in the embryo".
Extracting test cells before the embryo divides a third time could reduce the number of misdiagnoses because of mosaicism, the UF scientists suggest. Improving culture conditions could help too, Kovalinskaia said.
But the small margin of error shouldn't stop couples from having preimplantation genetic diagnosis, said Dr. Jamie Grifo, a professor of obstetrics and gynecology at New York University. The testing can work miracles for women prone to miscarriages or who carry genetic diseases, he said.
"If you are at risk for genetic diseases, it changes your outlook on starting a family," he said. "PGD allows them to get pregnant. It's a dramatic improvement when it works".
More than 45,000 babies are born each year with the aid of assisted reproductive technologies like IVF, according to the Centers for Disease Control and Prevention. The use of IVF has declined in recent years, but Grifo said that is largely because baby boomers are leaving their childbearing years. Technologies like preimplantation genetic diagnosis have helped too, making IVF more accurate, he said.
"There has been a lot of progress," Grifo said. "It's helped a number of patients".
Source: University of Florida
Did you know?
Screening embryos for genetic diseases during in vitro fertilization offers couples the best chance for a healthy child, but a genetic glitch could potentially cause doctors to misdiagnose a small fraction of them, University of Florida scientists say. Citing concerns about the accuracy of preimplantation genetic diagnosis, the method a number of practitioners use to pick the healthiest embryos during IVF, UF scientists set out to study the procedure. Their work, described during a recent meeting of the American Society of Reproductive Medicine, reveals the technique is actually highly reliable. But because there is a slim chance a genetic abnormality can cause doctors to misdiagnose embryos, some concerns still need to be addressed, the scientists said.
Medicineworld.org: Genetic Testing Still Smart Choice
The contents of this web page are protected. Legal action may follow for reproduction of materials without permission.