Entries in Whole Genome Sequencing (2)


Genome Sequencing Making Fetal Health Testing Easier, Raising Questions

Stockbyte/Thinkstock(STANFORD, Calif.) -- A new test is making it easier to determine the health of a fetus. But this new method to inform expecting parents about whether their late-term baby will be born with health problems also raises ethical questions.
In the past, doctors took a sample from the fetus to get a complete genetic sequence that could offer clues on possible diseases or defects that would need to be remedied. But that test could also harm the fetus. That danger changed a month ago when researchers simply took a sample from the mother's blood and the father's saliva.

Now researchers at Stanford University have simplified the process even more. They used only blood samples from two pregnant women, one with a healthy fetus, the other with a rare genetic disorder. The test results matched each baby's condition after birth. The entire process was completed without the paternal DNA.
This new method, which can be performed in the first trimester, leaves enough time to detect and treat diseases during pregnancy and prevents others by showing moms what foods to avoid during pregnancy.
But despite the test's usefulness, the researchers fear it could compromise ethics. In about three years, the new technology could determine the complete genetic sequence of an unborn child, and those results, some fear, could lead prospective parents to terminate pregnancies they wouldn't have otherwise.
Copyright 2012 ABC News Radio


DNA Testing Not So Potent for Prevention, Study Says

Comstock/Thinkstock(BALTIMORE) -- When scientists developed the ability to catalog a person’s genes, many hailed whole genome sequencing as modern medicine’s best tool to predict and prevent serious diseases, such as cancer. But according to a new study, whole genome sequencing is not the magic bullet for prevention -- at least not yet.

A team of researchers from Johns Hopkins Kimmel Cancer Center found that the test fails to provide solid predictive evidence for a large portion of people. The findings were published online Monday in the journal Science Translational Medicine.

“From a public health perspective, basically, it’s a reality check. It tells us what will we be able to do, and what won’t we be able to do with whole genome sequencing,” said Dr. Bert Vogelstein, co-director of the Hopkins’ Ludwig Center for Cancer Biology Research in Baltimore, and an author of the study.

The researchers analyzed data from thousands of identical twins, noting how many of them had developed any of 24 different diseases, including cancer and autoimmune, cardiovascular, genitourinary, neurological and obesity-related disorders.

Vogelstein said data from identical twins, who share the same genome, give scientists an opportunity to study the genetic components of disease. If the genome was the determining factor for common diseases, then the number of twins who have a certain disease that their twin also has could show how well whole genome sequencing could predict an individual’s disease risk, he said.

Using what they knew about how many of the twins developed certain disorders, the researchers created a mathematical model to calculate the capacity of whole genome sequencing to predict the risk of each disease.   

They found that the majority of people would receive negative results for 23 of the 24 diseases, even though the risk of developing 19 of them in people who tested negative would still be 50 to 80 percent of the risk in the general population. The researchers reported that the best-case scenario would mean that 90 percent of people tested would be alerted to a clinically significant predisposition to at least one disease.

Vogelstein told ABC News that the study found that whole genome sequencing is not a perfect predictor of a person’s future health.

“In some cases people may find it useful, but others will decide that it’s less useful,” Vogelstein said. “All we’re trying to do is provide the limits so people will know what they’re paying for and what the capacity is of these tests.”

A number of private labs provide whole genome sequencing services for about $3,000 per genome, but prices are dropping as the technology improves.

Dr. Ronald Crystal, chairman of genetic medicine at Weill Cornell Medical College in New York City, said the tests are still a valuable way to test for the risk of certain diseases that have definite genetic links, such as Alzheimer’s disease or type 1 diabetes. But for many diseases, for example cancer, which are shaped by a symphony of genetic, environmental and behavioral risk factors, scientists still need much more research before learning what genetic results mean for a specific individual’s risk.

“In terms of disease prevention, what we tell patients now still holds:  Don’t smoke, don’t do drugs, don’t be obese, eat sensibly and exercise,” Crystal said.

Copyright 2012 ABC News Radio

ABC News Radio