Prevent Disease.com - Test Can Screen for Down Syndrome in 1st Trimester



		Test Can Screen for Down Syndrome in 1st Trimester NEW YORK (Reuters Health) - A new screening test could help diagnose Down syndrome in fetuses as young as 11 weeks, British researchers report. Currently, the disorder is not diagnosed until early in the second trimester through invasive tests such as blood screening and amniocentesis. The new technique uses ultrasound, a noninvasive procedure, to detect the presence of a nasal bone. Down syndrome, also known as trisomy 21, is the most common identified cause of mental retardation in the US, affecting about 1 in 800 infants. People with the disorder have an extra chromosome and tend to have slanting eyes, small noses, broad hands and short fingers. In the study, the investigators performed ultrasound on 701 fetuses between 11 and 14 weeks gestation, looking specifically at the profile. More than half of expectant mothers were at least 38 years old, putting them at increased risk of having a child with Down syndrome. According to new study findings in the November 17th issue of The Lancet, a nasal bone was absent in nearly three quarters (73%) of fetuses that were determined to have an extra chromosome in a laboratory test performed immediately after the ultrasound. What's more, the ``false-positive'' rate, or the percentage of fetuses that were mistakenly diagnosed with Down syndrome because a nose bone could not be detected, was 0.5%. Current screening methods, which include a combination of the mother's age, blood tests and features seen on an ultrasound scan, have a false-positive rate of 1% to 5%. The researchers, led by Dr. Simona Cicero from King's College in London, UK, estimate that the findings, if confirmed by additional studies, could lead to a fivefold reduction in the rate of miscarriage caused by invasive testing methods. In an editorial accompanying the report, Dr. Howard Cuckle from the University of Leeds, UK, adds that an earlier diagnosis could also result in safer and less traumatic abortions and, for most women, the reassurance that their baby is healthy. SOURCE: The Lancet 2001;358:1658-1659, 1665-1667. Reference Source 89 For more information on how to prevent other diseases, use PreventDisease.com's "Quick Prevention Resources".