A safe method for early diagnosis of Down syndrome and other trisomies

Researchers from Stanford University have learned to diagnose Down syndrome in a fetus from a blood test of the mother. Unlike the invasive methods currently used, the new test is safer because it is not associated with the risk of miscarriage, the journal Proceedings of the National Academy of Sciences reports.

Down syndrome is a severe chromosomal abnormality in which an embryo has three copies of the 21st chromosome instead of two. To diagnose the disease in utero, as well as to decide on an abortion, methods such as amniocentesis (examination of amniotic fluid) and chorionic villus biopsy are currently used. Both of these methods are associated with a 1% risk of miscarriage.

A new, safe method for diagnosing Down syndrome is based on determining the number of fragments of the 21st chromosome in the mother's blood.

Using the DNA sequencing method, study leader Stephen Quake and his colleagues examined blood samples from 18 pregnant women. With the help of the test, they managed to diagnose nine cases of Down syndrome with absolute accuracy. According to scientists, in the presence of this disease in the fetus, 11% more fragments of the 21st chromosome were detected in the blood of their mothers than in the absence of pathology.

In addition, the researchers were able to accurately identify two cases of trisomy of the 18th chromosome (Edwards syndrome) and one case of trisomy of the 13th chromosome (Patau syndrome). Edwards syndrome and Patau syndrome are severe chromosomal abnormalities that often lead to the death of a child during the first year of life.

In contrast to the invasive methods of diagnosing Down syndrome, usually prescribed after the 15th week of pregnancy, a new test can be performed significantly earlier – at 5 weeks after conception, Quake said. An additional advantage is that the results of the study become known within a few days instead of two or three weeks, he stressed.

Currently, scientists are planning to conduct a larger study involving several hundred pregnant women. If it is successful, the new test will become widely available within two or three years, and the study will become one of the standard methods for diagnosing fetal health.

Copper News based on New Scientist – Blood tests could eliminate Down's miscarriage risk

Portal "Eternal youth" www.vechnayamolodost.ru08.10.2008