Featured Research

from universities, journals, and other organizations

Prenatal Biochemical Screening Only Detects Half Of Chromosomal Abnormalities

Date:
June 5, 2008
Source:
European Society of Human Genetics
Summary:
Prenatal biochemical screening tests are widely used to look for chromosomal abnormalities in the fetus which can lead to serious handicap, or even death during gestation or in the first few days after birth. But these tests are only able to detect fewer than half of the total chromosomal abnormalities in the fetus.

Prenatal biochemical screening tests are widely used to look for chromosomal abnormalities in the fetus which can lead to serious handicap, or even death during gestation or in the first few days after birth. But these tests are only able to detect fewer than half of the total chromosomal abnormalities in the fetus, a scientist will tell the annual conference of the European Society of Human Genetics on June 2. Dr. Francesca R. Grati, of the TOMA Laboratory, Busto Arsizio, Italy, says that these findings mean that women should be better informed on the limitations of such diagnostic tests.

The researchers studied 115,576 prenatal diagnoses carried out during the last fourteen years. 84,847 were amniocenteses, usually carried out around the 16th week of pregnancy, and 30,729 chorionic villus samplings, which can be undertaken from 12 weeks into the pregnancy. Both these tests carry an increased risk of miscarriage, so the decision on whether or not to undertake them can be difficult to weigh up. "Since our sample included a large number of women aged less than 35 who underwent invasive prenatal diagnosis without any pathological indication to do so, we felt that the results could be useful in helping to inform pre-test counselling of such women", says Dr. Grati. "Up until now, the information we had came from smaller studies which only looked at the performance of these tests in detecting a limited number of chromosomal abnormalities."

After analysing the results of the chromosomal abnormalities from their own dataset, the researchers combined them with the official detection rates for these abnormalities published by SURUSS and FASTER consortia. These are multi-centre research groups involved in the investigation of screening and diagnostic tests performed in pregnancy, whose results are being used to optimise prenatal care for pregnant patients. They found that current screening procedures were only able to detect half the total chromosomal abnormalities in women both younger and older than 35.

The TOMA laboratory is particularly suited to carry out this kind of research, says Dr. Grati, because it was among the first in the world to deal with prenatal diagnosis, and has a vast number of prenatal diagnostic samples at its disposal.

Current tests do not detect all fetal chromosomal abnormalities, but only trisomies 21 (Down syndrome), 18 (Edward's syndrome), and 13 (Patau syndrome), monosomy X (Turner syndrome), and triploids (conceptuses with 69 chromosomes instead of 46). "These are common vital chromosomal abnormalities, but there are many others which are not picked up by these tests", says Dr. Grati. "And the tests do not even detect 100% of the common abnormalities."

At conception, 23 chromosomes from each parent combine to create a fetus with 46 chromosomes in all its cells. Trisomy occurs when the fetus has one additional chromosome (47 instead 46). The extra genetic material from the additional chromosome causes a range of problems of varying severity.

In Down syndrome, for example, where the fetus has three copies of chromosome 21, babies are usually born with impaired cognitive ability and physical growth, cardiac defects and a characteristic facial appearance. Unlike many other such abnormalities, however, babies born with Down syndrome are able to lead relatively normal lives and their life expectancy is around 50 years.

Other than trisomy, the fetus can also have the loss of genetic material (deletions) or chromosomal abnormalities in a non-homogeneous form, where there is a mixture of two cell lines, one normal and the other abnormal. "Some of these disorders are relatively common in the fetus, which may have as much chance of surviving as children who are born with Down syndrome, and it is worrying that current biochemical tests are not always able to detect them" says Dr. Grati. "Our research confirms that it is fundamental for doctors to counsel patients about the limitations of current screening methods, so that they can make an informed decision on whether or not to undergo invasive diagnostic testing."


Story Source:

The above story is based on materials provided by European Society of Human Genetics. Note: Materials may be edited for content and length.


Cite This Page:

European Society of Human Genetics. "Prenatal Biochemical Screening Only Detects Half Of Chromosomal Abnormalities." ScienceDaily. ScienceDaily, 5 June 2008. <www.sciencedaily.com/releases/2008/06/080602075834.htm>.
European Society of Human Genetics. (2008, June 5). Prenatal Biochemical Screening Only Detects Half Of Chromosomal Abnormalities. ScienceDaily. Retrieved October 22, 2014 from www.sciencedaily.com/releases/2008/06/080602075834.htm
European Society of Human Genetics. "Prenatal Biochemical Screening Only Detects Half Of Chromosomal Abnormalities." ScienceDaily. www.sciencedaily.com/releases/2008/06/080602075834.htm (accessed October 22, 2014).

Share This



More Health & Medicine News

Wednesday, October 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Orthodontist Mom Jennifer Salzer on the Best Time for Braces

Orthodontist Mom Jennifer Salzer on the Best Time for Braces

Working Mother (Oct. 22, 2014) Is your child ready? Video provided by Working Mother
Powered by NewsLook.com
U.S. Issues Ebola Travel Restrictions, Are Visa Bans Next?

U.S. Issues Ebola Travel Restrictions, Are Visa Bans Next?

Newsy (Oct. 22, 2014) Now that the U.S. is restricting travel from West Africa, some are dropping questions about a travel ban and instead asking about visa bans. Video provided by Newsy
Powered by NewsLook.com
US to Track Everyone Coming from Ebola Nations

US to Track Everyone Coming from Ebola Nations

AP (Oct. 22, 2014) Stepping up their vigilance against Ebola, federal authorities said Wednesday that everyone traveling into the US from Ebola-stricken nations will be monitored for symptoms for 21 days. (Oct. 22) Video provided by AP
Powered by NewsLook.com
Doctors Help Paralysed Man Walk Again, Patient in Disbelief

Doctors Help Paralysed Man Walk Again, Patient in Disbelief

AFP (Oct. 22, 2014) Polish doctors describe how they helped a paralysed man walk again, with the patient in disbelief at the return of sensation to his legs. Duration: 1:04 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins