A New Non-invasive Test for Down's Syndrome

26 November 2000


Researchers have developed a non-invasive test that can determine whether a developing baby has Down's syndrome, a condition caused by the baby having an extra chromosome no. 21. Until now the only way to diagnose the condition was to take a small sample of the fluid surrounding the baby, called amniocentesis. Cells in the fluid from the baby can then be analysed to see if they have the extra chromosome. Unfortunately the test carries a risk of miscarriage in about 1% of cases. In the new test, a research team from Hong Kong led by Dr. Dennis Lo have found that they can extract intact foetal cells from the mother's blood, meaning that a simple blood test is all that is required so there is no risk to the baby. The foetal cells can be analysed under the microscope with a dye that selectively labels chromosome 21. Any cells containing more than 2 chromosome 21 signals (which is the correct number) indicate that the baby may have Down's syndrome. New ultrasound findings provided additional test for Down's Syndrome.


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