Embryos, at just eight cells, can now be screened using chips called microarrays. Each chip is layered with DNA fragments. They're scanned for thousands of specific genetic defects all at once.
"We try to hone in on the most common disorders that we see in healthy couples," said Dr. Jeffrey Steinberg, Medical Director of the Fertility Institutes in Encino, California.
Dr. Steinberg says the test looks for genetic causes of Down's syndrome and the risks of prostate, breast and colon cancers. But experts caution: DNA doesn't determine everything.
"If you do a DNA test on someone to predict their risk of heart disease, you're really only looking at a part of the picture," said Dr. Marta Gwinn, Associate Director of Epidemiology at the National Office of Public Health Genomics in Washington, D.C. "You're really only looking at what they came with, the hand they were dealt."
At 39, Mary -- and 55-year-old Roy -- know age is a risk factor, but they also want to avoid passing along a family history of cancer and heart disease.
"Growing up and later discovering you had a genetic disposition passed on from family members, if you can eliminate that and save yourself and your family members so much pain, I think that this is amazing," Mary said.
At about $20,000 a couple, this isn't for everybody. But for Mary and Roy, if it means the chance of a healthy sibling for 3-year-old Ava, it's worth it.
While it's possible to test for some adult-onset diseases as well as eye color, Dr. Steinberg says it's best for couples who have a known family disorder that's genetic in nature or someone with a history of miscarriage.
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