Lakshmi Mehta, M.D Medical Genetics from Mount Sinai Medical Center talks about Down Syndrome.
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Host: The only big concern is, I don’t want my kid to have Down syndrome and I am 35 years older. Why do they worry about the age of 35 year older, is that a reason? Lakshmi Mehta: Well, the 35 is not really a magic number. Host: Well, something like that. Lakshmi Mehta: You don’t actually develop -- Host: If the women is trying to improve the about your age, what age would you do worry, 35, 38? Lakshmi Mehta: Well, the actual risk for Down syndrome in when a woman is about 35 years is like a 0.5%, so it’s about 1 in 200. Why that number keeps coming up is because when people are offered them using pessus, the risk of having using peasese is about a half percent so they picked 35 as the age where it balances the rest. Host: Neutral, okay, so 38 year old. Lakshmi Mehta: Has about a little higher 0.8%. Host And about a 40 year-old? Lakshmi Mehta: 40s about like 1, 2% and then it starts creeping up. Now today we have basically very kind of like screening programs that are available with a lot of debate about what is the best screening program for Down syndrome to offer a woman. We have a very early test, it’s called the ultra screen, which is done around even before like 9 to 10 weeks, 9 to 10, 11 weeks of pregnancy. And in that test you measure the size of the back of the neck of the fetus or it’s called a nuchal fold. And along with that -- Host: On with help of a sound? Lakshmi Mehta: By RF sound and along with that, they do free chemicals in the block and the combination of -- Host: What chemicals are usual? Lakshmi Mehta: They do HCG, they do PAPP-A and they do the nuchal thickening, so the three things together give you the risk at 9 to 10 weeks if that’s elevated and they combine it with the mother’s age, so they give you a risk figure of how likely it is based on these things that the person could be carrying a baby with Down syndrome. If that’s elevated, she can be offered an early test called the CVS test, which is done up to 12 weeks usually and she will know what comes out of the baby by that time. There is a second stage of its screening is done which is at 15 weeks in the pregnancy where again you do some of the syndrome chemistry, AFP, estriol, an HCG and then you give a risk at that point. Then there is ultrasound. Ultrasound can pick up lots of what we call soft markers, which may suggest Down syndrome. So this multiple levels at which pregnancies can be screened when you are not even 35 or even some 35, 38 year-old women who don’t want an MU could go through the screening tests. And if there is a suspicion that can be offered by MU, which is the definitive test. There is only one definitive test, it will tell you what the components are, and that’s either the MU or better you test called CVS. Host: They didn’t know, she did know -- and she has a kid born with Down syndrome. If she got pregnant again, what’s the risk of the next pregnancy? Lakshmi Mehta: It’s pretty low, so it could be above 1% we say because we’re not exactly 100% sure, what causes that extra chromosome to creeping is called nondisjunction, so it’s like a pair of chromosomes given the separate thing and to crept into one egg or one sperm. We would say about 1% or her age rated risk, which is at 42 or 45 is more than 1% Host: is there a certain thing called translocation of -- they look normal or what’s look better? Lakshmi Mehta: Right. About 94, 95% of babies with Down syndrome have the trisomy, the whole extra of number 21 chromosome which is what we said a sporadic event that you know, not inherited but may be about 3, 4% of Down syndrome babies have the extra 20s, and 21 chromosome sitting on top of another chromosome, which is called a translocation. So it’s not lying free, that’s a good reason to test every single baby with Down syndrome. Even though you know they have Down syndrome, you should establish that whether they have a trisomy or a translocation because if it’s a translocation the parent should be tested, one of them could be t
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