The main options for parents who want to test their unborn child for genetic diseases are invasive procedures that pose up to a 1 percent risk of miscarriage. But in landmark studies published last year, two research teams pieced together nearly an entire fetal genome using just easy-to-obtain parental blood and saliva samples.
One technique, [pdf] developed by University of Washington geneticist Jay Shendure, involves comparing fetal DNA from the mother’s blood plasma with DNA from the mother’s blood and from the father’s saliva. A statistical algorithm then analyzes which gene variants the fetus has inherited from each parent and detects new mutations in the child’s DNA.
A similar technique, created by researchers at Stanford, requires only blood from the mother, but provides less hereditary information. Both methods have downsides: They could flood parents with ambiguous genetic information, or encourage selective abortions for nonmedical reasons. Nevertheless, Shendure thinks that within five to ten years such tests could become the standard for early detection of genetic conditions such as cystic fibrosis and Tay-Sachs disease.
