Could embryonic screening eliminate diseases?

Could embryonic screenings eliminate diseases?

There is a breakthrough in reproductive technology, allowing for the screening of embryos before being transferred into a woman's uterus. It looks for diseases ranging from cystic fibrosis to Down syndrome.

In this special report, 7News takes you inside an embryo lab at Woman's Hospital in Baton Rouge to find out what the screenings mean for couples looking to have a healthy baby.

Inside the highly secured, temperature and germ-controlled room at Woman's Hospital, the components needed to create life are stored in liquid nitrogen. "Most of these tanks are sperm, some have eggs and embryos," said Richard Cochran, Ph. D, who is the scientific director at A Woman's Center for Reproductive Medicine.

Drs. Richard Cochran and Bobby Webster help couples with fertility problems conceive in a laboratory setting, oftentimes joining the egg and sperm in a petri dish, a process called in vitro fertilization. "As we've advanced, we've learned truly how inefficient the human reproductive system is," said Dr. Webster, "and that's totally different than you get in your high school biology class."

Something else you probably did not learn in biology class is a process called "preimplantation genetic screening," or PGS, a technology so new that it is still considered experimental, unless the couple has a history of genetic disorders. "If we're looking for a specific problem, we will not only offer it, but encourage it," said Dr. Webster.

That could be a history of cystic fibrosis in the family, sickle cell disease and spinal muscular atrophy. "These autosomal recessives are sitting, waiting for a match with someone else that's a carrier," said Dr. Webster.

Once a couple's embryos reach the three day mark, they are ready for biopsy. "We put the embryos in drops in a dish in the center of the screen to extract the necessary cell," said Dr. Cochran.

"By taking a set of cells on day five," said Dr. Webster, "we don't have to get into what's called the inner cell mast. We can biopsy some of the periphery cells."

Those cells then grow chromosomes that should be an exact copy of the embryo on day five, when they are ready for transfer to a uterus.

The screening results can be three-fold. "Normal, if it's a recessive disease," said Dr. Webster, "carrier, or diseased."

Once the results of the genetic testing are available, then the embryos that are not diseased will be taken out of an incubator and evaluated before being transferred into the mother. "It depends on how fast they've been dividing and the symmetry of the cells," said Dr. Webster, "and it's kind of a beauty contest on day five."

So what about the diseased embryos or the ones that did not win the day five beauty contest? On average, a couple will have five to eight leftover and in Louisiana, those embryos are protected as "people," meaning they cannot be destroyed - only frozen - or donated to another couple. "Those are theirs and sometimes they don't want to freeze them, they don't want to donate them," said Dr. Webster, "and they'll say, 'Okay, ship my embryos out of state,' and they do it out of state."

If used for good, these fertility experts say healthy, loved children can be brought into families. "What we're doing is helping to bring children into the most wanted environments in the world," said Dr. Webster, "I think it's a glorious, ethical goal to try to bring disease-free children into the world."

But this knowledge also has the potential to push slightly defective embryos aside, even unwanted boy or girl embryos. They are shaky ethical grounds, already being walked.

Preimplantation genetic screening costs about $3,500 and can screen for about 15 disorders. There are companies now offering screenings for 100 diseases and those could be available within six months.

In our final story on genetic selection Wednesday night on Nightcast, we will talk about Down syndrome, the most common genetic disorder, and why the termination rate nationwide is 90 percent.

This special report is part of a three part series on genetic testing.  Links to the two related pieces are below:
Genetic testing of a fetus offered for pregnant women
*Investigating 90% termination rate for Down syndrome fetuses

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