Your Baby, Bit by Bit

In this day and age, more and more women are postponing childbirth. When they're ready to conceive, though, they often worry that their baby will carry a genetic defect. Today a variety of genetic tests are available, but results must be confirmed through invasive procedures which carry a relatively high risk of miscarriage.

Scientists predicted a non-invasive, risk-free technique was close when they discovered fragments of fetal DNA are present in the mother's blood, enough to construct the fetus' entire genome. This was confirmed recently by the successful sequencing of the genome of an 18-week-old fetus. Later, when compared with the baby's genome after birth, the technique was 98 percent accurate - a major breakthrough in fetal genetic testing.

To do this, researchers had to differentiate fetal DNA from its mother's. First, they got cells from the father's saliva to yield his genomic sequence. Then, they sequenced the mother's genome from her blood. Finally, they isolated all the DNA fragments in the plasma portion of the mother's blood, of which ten percent belongs to the fetus. Having sequenced the genomes of both parents, researchers could then pick out the fetal DNA and reassemble them to complete the fetal genome. Scientists believe the technique may even work on a six-week-old fetus.

Getting the cost down will be key to making it available in your doctor's office. The cost now is $50,000 per child. Though parents could have their baby's entire fetal genome sequenced, it still won't rule out all genetic diseases. Only a fraction of the genes behind birth defects are known, and some merely predispose a person to disease.

In the future, geneticists will identify disease-causing genes as well as genes behind traits such as intelligence and athletic ability. And so the designer baby debate will begin in earnest.