Down Syndrome is a genetic disorder that occurs at the same moment of conception, when the egg and the sperm are united. The cause that causes it is, until now, unknown. Anyone can have a child with Down Syndrome, regardless of race, creed or social status.
We all have 46 chromosomes in each of our cells; 23 come from the mother and 23 from the father. Both may possess one more chromosome, either in the ovum or in the sperm. In this way one of the two will contribute 24 instead of 23 chromosomes and will then be born a person with Down Syndrome, which will have a total of 47 chromosomes, instead of the corresponding 46. That extra chromosome will be housed in par 21, so it is known as TRISOMIA 21 (3 copies of chromosome 21).
As a consequence, their development is different and they present varying levels of learning difficulty. It is also common for them to have medical complications such as hearing, thyroid, bowel and heart problems. The World Health Organization (WHO) estimates that one in 1,000 or 1,100 babies are born with Down syndrome worldwide.
In the United Kingdom there are about 750 births per year and an estimated 40,000 people live there with this genetic disease. 90% of Britons decide to abort when they learn that their child has this genetic disease. Now that it will be possible to know with 99% effectiveness, there are those who fear that more parents choose that option.
Now a highly accurate, noninvasive test to identify this condition in the early stages of pregnancy sparked a debate in the UK as it could lead to even more abortions and, in the future, to their virtual disappearance. But there are those who want to keep Down syndrome from being eradicated.
So far, the UK National Health Service has provided all pregnant women with evidence to see if the fetus had the condition at 85-90% accuracy. However, 2.5% of the results were false positives.
There are other tests, such as amniocentesis or chorionic villus biopsy, that can accurately determine the presence of the extra copy of chromosome 21. The problem is that both studies are invasive, that is, a needle is used to take a sample from the fluid that envelops the baby or placental cells. This presents a risk of spontaneous abortion, something that not all women are willing to run.
The new studies:
In this context, the non-invasive prenatal blood test (NIPT) arouses as much hope as controversy.
The UK announced that this test, already available in some 100 nations around the world, will soon be offered to all women in the country as a second step in the monitoring process.
The NIPT has an accuracy of 99% and does not present risks of miscarriage. Thus, false positives would be avoided and invasive testing would be substantially reduced.
In Iceland, currently almost all pregnant women are tested for Down syndrome and almost 100% of women with a positive diagnosis choose to have an abortion.