Skip main navigation

£199.99 £139.99 for one year of Unlimited learning. Offer ends on 28 February 2023 at 23:59 (UTC). T&Cs apply

Find out more

Genomic technologies in prenatal diagnosis

In this step, we will hear how genomic technologies have impacted on the practice of fetal medicine
I’m a consultant obstetrician who specialises in foetal medicine. And therefore I mostly see parents where the pregnancy isn’t going quite right, or there is a risk in the pregnancy that they’re concerned about. For example, they may have had a scan which shows a structural problem in the baby, or they may have an increased risk of Down syndrome, or the baby may not be growing well. Any sort of concern about the baby’s development is usually the area in which I’m involved. I think genomic testing has completely changed the way in which we practise clinical medicine and given opportunities for women that they previously didn’t have. In the first instance, it’s noninvasive prenatal testing.
And that’s by measuring foetal DNA in the mother’s bloodstream. And that has completely changed how we’re able to screen for things like Down syndrome and some single-gene disorders, and also for some sex-linked disorders, by measuring the amount of baby’s DNA that’s circulating. It’s a safe test and usually very, very effective and very efficient in testing. Secondly, we’ve had the introduction of prenatal arrays into prenatal diagnostics. So when we do an amniocentesis or a CVS, and we get a sample, we traditionally used to do a karyotype, which was just counting the number of chromosomes and looking at it visually to see whether they’d look normal. And now we’re able to, using prenatal arrays, look in much more detail.
And by doing so, we’re able to pick up diagnoses that were conventionally missed by the old tests. So I think both of these have changed both the safety of what we do and also increased how good we are at diagnosing problems that we missed in the past. Patients have grasped and really encouraged noninvasive prenatal testing. I think from a woman’s perspective, being able to have a safe test that doesn’t confer the risk of miscarriage is extremely wanted and desired. The fact that it also comes along with a very high screening efficiency– that means it’s very accurate, in terms of picking up the vast majority of problems– means that it’s a win-win situation for the women.
When we offer prenatal arrays, on the whole, it’s well received, because most of the parents we do diagnostic testing on have a problem that they think is going on. So the baby may have a structural problem, or there may be concerns about the well-being of the baby’s growth, for example. So, on the whole, they want to know as much information as they can get, if they’re going to risk a miscarriage by having an invasive test. However, there are some downsides in that prenatal arrays can bring up information that is either difficult to interpret or of unknown significance. And that is a qualification we have to tell parents.
And they’re sometimes a bit worried about the possibility of getting information that either the professional or themselves don’t understand. But on the whole, that is a pretty infrequent problem and completely outweighed by the advantages of being able to make diagnoses. I think the potential is huge, in terms of diagnostic testing and prenatal arrays. Almost certainly, I think, we will expand into exome sequencing and most probably full sequencing, as well. I think that’s most likely. But what’s going to hold us back is being able to handle the amount of information that more analysis gives us and able to understand that information and translate that information to the women.
Because as you look in more and more detail, you find things that you haven’t seen before. And you have to make a judgement call as to whether this genomic information is of significance to that particular patient and the particular situation you’re in, or whether it is completely irrelevant. But what it will help us with is that currently we see a lot of women where there are problems in the babies, and we have no idea why they’re occurring. And I think being able to rationalise why they’re occurring is an important step for the parents to understand what’s happened to them.
It’s a very important step for us, to be able to know how to manage these pregnancies, given the genetic information that we’re getting. I think the major battle with the new technologies, especially in the genetics field, is the fact that the health-care workers need to understand this technology in order to be able to explain it to patients and parents. And that is a difficult area. So I think this course is perfectly aimed at trying to do that.

Dr Basky Thilaganathan, Professor of Fetal Medicine, discusses how genomic technologies have impacted on the practice of fetal medicine.

This article is from the free online

The Genomics Era: the Future of Genetics in Medicine

Created by
FutureLearn - Learning For Life

Our purpose is to transform access to education.

We offer a diverse selection of courses from leading universities and cultural institutions from around the world. These are delivered one step at a time, and are accessible on mobile, tablet and desktop, so you can fit learning around your life.

We believe learning should be an enjoyable, social experience, so our courses offer the opportunity to discuss what you’re learning with others as you go, helping you make fresh discoveries and form new ideas.
You can unlock new opportunities with unlimited access to hundreds of online short courses for a year by subscribing to our Unlimited package. Build your knowledge with top universities and organisations.

Learn more about how FutureLearn is transforming access to education