Researchers found a safer method to diagnose Down’s syndrome and several other genetic disorders, a method that at some point may become available by using a genetic test performed on blood samples collected from expectant women.

Pregnant women preoccupied with their babies’ genetic health currently have two possibilities at their disposal: the first one – to get prenatal testing and maybe undergo miscarriage, and the second one – to avoid genetic tests and not be aware of their babies’ such genetic defects before the moment of birth.

Researchers from Stanford University in California and the Howard Hughes Medical Institute created and used a new method able to search for the extra chromosomes that cause Down’s syndrome and other birth defects in the fetal DNA in maternal blood.

This test, a gene-sequencing one, only requires a tiny blood sample from the pregnant woman, compared to amniocentesis, which is performed with a needle inserted through the maternal abdomen into the uterus and amniotic sac. Therefore, one can draw the conclusion that this novel approach is safer that amniocentesis. As stated by the Royal College of Obstetricians and Gynaecologists, about 1 in every 100 expectant women who get an amniocentesis will consequently miscarry.

“We look for chromosomes that are overrepresented,” said study author Stephen Quake, a professor of bioengineering and applied physics at Stanford and the Howard Hughes Medical Institute. “The breakthrough is we're able to measure very slight differences very accurately,” he added.

Down syndrome, also called Trisomy 21, is a chromosomal disorder triggered by the presence of all or part of an extra 21st chromosome. Doctors can identify the syndrome during pregnancy or at birth. This genetic birth disorder, the most common one, which causes mental retardation and other problems, occurs in 1 in every 700 infants.

The same test is also able to spot other chromosomal disorders such as Edward syndrome (Trisomy 18), which kills half of babies in the first week of life and those who survive almost always have problems with their heart, lungs and digestive system, and Patau syndrome (Trisomy 13), which usually kills over 80% of children during infanthood. Patau syndrome affects about 1 in every 12,000 live births.

The results of a study of 18 pregnant women and one man for comparison allowed researchers to identify signs of chromosomal disorders. Scientists collected blood samples from the 10 to 35 weeks pregnant women at the Prenatal Diagnostic Center at Lucile Packard Children's Hospital. The new method was used after doctors performed amniocentesis. The findings, which appeared in the online issue of the Proceedings of the National Academy of Sciences, don’t present much precision and reliability; therefore, additional research would have to be done.


With the help of the new approach, researchers diagnosed nine cases of Down’s syndrome, two cases of Edward syndrome and one case of Patau syndrome.

According to Carol Boys, director of the Down's Syndrome Association, "there is no question” that the non-invasive test will be available in a couple of years.