Biotech Companies Developing Blood Tests for Down Syndrome

 

Andy with his sisters, 4-year-old Lily and 8-year-old Kate

Andy with his sisters Lily and Kate

Two biotech companies, Artemis and Sequenom, are developing prenatal blood tests to detect Trisomy 21, the chromosomal abnormality that causes Down syndrome.

These blood tests are non-invasive and can be done in the first trimester of pregnancy.

According to Ian Clements, spokesperson for the San Diego-based publicly-traded Sequenom, the company recently completed a successful study of the plasma of about 480 women, which they plan to publish soon.

Clements said Sequenom’s next step is to do a much bigger study, in conjunction with Women and Infants Hospital of Rhode Island, which has been gathering thousands of blood samples of high-risk pregnant women.

Once they obtain the results of that study, Sequenom hopes to make the test commercially available.

Physicians will order the blood draw and send it to Sequenom’s laboratories in San Diego to be tested, Clements said.

“We’re obviously pretty hopeful and confident based on the study we’ve done on the smaller sample set,” Clements said.

Currently, although preliminary blood work can give women a prediction of the odds of the fetus having chromosome abnormalities, there are only two definitive ways to test for Down syndrome. Both tests are invasive:

Amniocentesis: This test is usually done after 15 weeks of pregnancy. A needle is inserted into the amniotic sac through the mother’s abdomen and fluid is taken out. The amniotic fluid is then tested for Down syndrome, spina bifida, and other abnormalities.

Risks of amniocentesis: According to the Mayo Clinic, doing an amniocentesis has a 1 in 300 to 1 in 500 risk of miscarriage. Other risks, which are less common, include cramping and vaginal bleeding, RH sensitization, needle injury to the baby, amniotic fluid leakage, and infection.

Chorionic Villus Sampling (CVS): This test is done between the 10th and 12th week of pregnancy. A tiny piece of the placenta is removed, either through the cervix (via a catheter that has a small suction on the end of it) or through the woman’s abdomen (with a long needle), and then tested for abnormalities.

Risks of CVS: According to the Mayo Clinic, the risk of miscarriage is 1 in 100. Other risks include cramping and vaginal bleeding, RH sensitization, and infection.

How common is Down syndrome?

Down syndrome occurs in about 1 in 800 pregnancies overall. The National Down Syndrome Society estimates that there are more than 400,000 people in the U.S. with Down syndrome today.

Though your risk for having a Down syndrome baby is higher the older you are, more women under 35 have babies with Down syndrome because so many more babies are born to women under 35.

According to the March of Dimes:

• At age 25, the risk of having a baby with Down syndrome is 1 in 1,250.

• At age 30, the risk is 1 in 1,000.

• At age 35, the risk is 1 in 400.

• At age 40, the risk is 1 in 100.

• At age 45, the risk is 1 in 30.

Depending on your age, the risk of miscarriage due to the invasive testing like amniocentesis or CVS may actually be higher than your risk of having a Down syndrome fetus.

 

Stephanie Meredith with her husband Justin and their three children: 10-year-old Andy, 8-year-old Kate, and 4-year-old Lily

Stephanie Meredith with her husband Justin and their three children: 10-year-old Andy, 8-year-old Kate, and 4-year-old Lily

Stephanie’s Story

Stephanie Meredith of Canton, Georgia was in her early twenties when her son Andy was born with Down syndrome.

“When we first got the diagnosis we were scared 23-year-old kids,” she told me in a phone interview this morning. “We had all these questions … questions about other kids being kind to him, what his future would be like. You have to adjust your expectations, but then life becomes remarkably ordinary and you love this little person and accept him for the individual that he is.”

Today Andy is ten years old. Meredith says he’s an amazing photographer and he loves to mountain bike. He gets extra help for math and reading, two subjects he struggles with. He studies social studies, science, art, music, and PE with his peers.

The Abortion Option

According to an article published in May 2007 in the New York Times, about 90 percent of women who find out they are carrying a Down syndrome fetus choose to have an abortion. A more recent ABC news story reported that Down syndrome birth rates have been dropping as more women choose genetic testing and then decide to abort.

But families living with Down syndrome believe that many of our culture’s ideas about Down syndrome are out of date.

“The outcomes for people with Down syndrome have improved so dramatically in the past 30 years,” says Meredith. “Providing fair, balanced, and accurate information is the absolute critical key, with Down syndrome and any other genetically diagnosed conditions.”

According to Meredith, who has written one printed booklet, “Understanding a Down Syndrome Diagnosis,” that has been nationally recommended by the Kennedy Foundation First Call Advisory Committee, and has also just launched a Website, DownSyndromePregnancy with an e-book (co-authored by Nancy Iannone) about Down syndrome to support women who chose to continue their pregnancies, some of our most basic notions about this condition are wrong.

“People might think there’s a higher divorce rate among couples who have a child with Down syndrome when actually the divorce rate is lower. A lot of people are concerned about the future and don’t realize there are over 250 college programs for people with disabilities. A lot of people worry about the possible implications for other children when the studies show that they end up being more compassionate and well-adjusted than other children,” Meredith said.

Still, Meredith thinks non-invasive testing can be a good option for pregnant women who want more information, even though some pregnant women might not want to know.

“I honestly think it gives people more information, then it’s up to them how they want to use it,” Meredith said.

What do you think? Did you choose to do genetic testing? Do you think it’s better to have an abortion if something is wrong with the fetus? Would you have an abortion if you knew you were carrying a Down syndrome fetus?

Related post: A Dad Writes About Raising a Daughter with CP
Elie’s Story: Velo-Cardio-Facial Syndrome


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