Genetic Motherlode: Scientists Decode an Unborn Baby's DNA

Posted: June 7, 2012 at 5:11 pm

Researchers at the University of Washington have sequenced the entire genome of a fetus. The scientific advance could help detect certain diseases in the womb, but some experts worry that the trove of genetic information may prove more scary and overwhelming than useful.

Suspended in the blood of a pregnant woman along with some added information from a dad-to-bes saliva lurks enough fetal DNA to map out an unborn babys entire genetic blueprint.

It may sound like something conjured by Jules Verne, but it happened at the University of Washington: a professor and his graduate student used DNA samples from the parents of a baby boy who was still in utero and reconstructed his entire genetic makeup from A to Z.

The account, published Wednesday in Science Translational Medicine, takes prenatal testing to new heights, promising a motherlode of genetic information about a child who had not even been born along with a corresponding trove of data that even experts dont yet know how to interpret.

Jacob Kitzman, lead author and a graduate student in the department of genome sciences at the University of Washington (UW), was excited but cautious about his teams achievement. There have been a lot of steps toward this, but this is the first time capturing the whole genome, says Kitzman. The fact that this technology is now on the path to becoming clinically feasible is a good opportunity for a broader discussion of the implications.

Figuring out how to communicate the vast cache of information uncovered by genome sequencing remains controversial, since much of it still isnt clinically useful. But although researchers dont understand the significance of the entirety of the information revealed through whole-genome sequencing, they do know that certain genes are responsible for Mendelian, or more simple, single-gene disorders that includes more than 3,000 conditions such as cystic fibrosis, Tay-Sachs disease and some muscular dystrophies that affect 1% of pregnancies. Prenatal sequencing would allow parents to learn before delivery if their child has one of these diseases, many of which are debilitating or fatal. While genetic screening of parents before pregnancy can also identify carriers, and an increasing number of prenatal DNA-based tests can determine early in pregnancy whether developing babies have specific conditions such as Down syndrome, whole-genome sequencing is the most sophisticated way to examine a persons entire genetic code.

(MORE:Down Syndrome: With Breakthroughs in Testing, a Choice Becomes Tougher)

Prenatal genome sequencing could potentially replace more invasive procedures such as amniocentesis or chorionic villus sampling to detect recessive Mendelian disorders on average, we all carry 20 to 30 recessive genes but it is not yet precise enough to take the place of these tests when looking for other chromosomal conditions. Nor is it a foolproof gauge of risk for many other complex diseases a category that includes most cancers and common conditions such as diabetes and heart disease because theyre influenced by multiple genes and environmental factors. Great, says Thomas Murray, president of the Hastings Center bioethics institute, we can sequence the genome of a fetus. What the hell does it tell us? Much less than most people probably believe.

Kitzman concurs. Its a really big challenge for the field, figuring out how to communicate to clinicians not only the results but the uncertainty that goes along with those results, he says. Theres no easy answer.

In this particular situation, Kitzman and Jay Shendure, an associate professor of genome sciences at UW, sidestepped the thorny issue of assessing disease risk and sharing that information with parents because the expectant couple was anonymous. Kitzman doesnt know their identity, only that they consented to have their biological samples used for genome sequencing. Their son was born healthy and full-term.

Continued here:
Genetic Motherlode: Scientists Decode an Unborn Baby's DNA

Related Post

Comments are closed.