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Prenatal Genetic Testing, and Down Syndrome

Lots of people don’t understand prenatal genetic testing, including both patients and doctors. For instance, many people think that the BUN genetic ultrasound or the “Quad screen” or the prenatal AFP tests can tell whether or not a baby has a genetic anomaly (they can’t; they can only indicate whether a fetus has an increased risk for a genetic anomaly), or that the tests are accurate in predicting whether or not babies have Down Syndrome (they’re not; only about 5% of mothers who test positive with standard methods actually have a baby with Down Syndrome, and even with the latest cell-free DNA method the proportion only goes up to 45%. An invasive procedure such as amniocentesis or CVS is necessary to confirm the accuracy of such testing).

A study in last week’s JAMA attempted to find what would happen if women were given a “decision support guide” to help them understand prenatal genetic testing. I doubt very much that the guide was slanted against genetic screening; yet when women were given more complete information than what is given in “usual care per current guidelines,” less women opted for genetic screening or invasive testing.

This study implies, of course, that “usual care” means that doctors are usually not fully informing women about these tests. And that is understandable, if not excusable, within the confines of a busy clinic schedule. It is much easier and quicker to say, “Do you want testing to see if your baby has any genetic defects?” — or, worse yet, “You need to get genetic testing because you’re over age 35″ — than to try to explain what is meant by “risk,” and that a positive result means almost nothing more than “You will need another test to interpret the result of this test.”

But if doctors don’t have enough time, or are not trained well enough or whatever, to give informed consent for testing that can have life or death consequences, if our usual and customary care is to do this testing without informed consent, then why is this testing considered standard of care?


On a separate but not unrelated topic,in a commentary published in Wednesday’s Chicago Tribune, a mother of a girl with Down Syndrome writes of the lessons she hopes her son will learn because he is growing up with a sister who has Down Syndrome. Here is an excerpt:

He will have a broader perspective of what “normal” is than most of his peers. Hearing his own sister being referred to as the “R-word” will enable him to teach those around him that it is wrong to dehumanize others with such offensive language. He will remind people that his sister has the right to be valued, respected and accepted — just like anyone else. He will be courageous and strong and will not allow bullying to be tolerated.

He will recognize that the diagnosis, condition or illness does not define the individual. It is simply a part of what makes him or her unique.

I hope this snippet will encourage you to read the entire article.

This entry was posted in Genetics, Health Care and tagged , , , . Posted by Joe Gibes. Bookmark the permalink.

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