The Society of Obstetricians and Gynecologists of Canada will recommend that all expectant mothers be offered screening for Down syndrome, but a group representing people with syndrome calls the draft recommendation discriminatory.

The prenatal screen for Down syndrome is now offered to women over 35 years of age. 

"We don't see it even as a medical condition."—Krista Flint, Canadian Down Syndrome Society

Last month, the American College of Obstetricians and Gynecologists began recommending that every pregnant woman, regardless of age, be offered a choice of tests for Down syndrome.

The college's Canadian counterpart is expected to do the same on Feb. 5 in its new recommendations, calling for all women to be offered non-invasive prenatal screening involving blood tests or ultrasound. 

About one in 800 babies has an extra, third copy of chromosome 21, or Down syndrome, also called trisomy 21. It affects mental capacity, and leads to a characteristic broad, flat face and small head and, often, serious heart defects.

Krista Flint, head of the Canadian Down Syndrome Society in Calgary, wants the society's recommendations to contain what she calls value-neutral language, such as referring to a determination rather than a diagnosis.

"We don't see it even as a medical condition," Flint said. "There are certainly medical conditions associated with Down syndrome, but the existence of the extra genetic material doesn't in and of itself make it a negative medical outcome."

Language used to describe Down syndrome, such as birth defect or anomaly, can be problematic because it doesn't give families a balanced view, Flint said.

So far, the society has been respectful about the concerns, she said.

Safer prenatal test

In related news, researchers in the U.S. announced a non-invasive test may pick up genetic conditions such as Down syndrome by examining fetal DNA.

Current tests, such as amniocentesis, analyze placenta cells to detect genetic abnormalities, but raise the risk of miscarriage.

In a preliminary study of 60 pregnant women, the new blood test correctly identified the presence or absence of Down syndrome in 58 cases. One case of Down was not identified and one was incorrectly identified, the team reported in Friday's issue of The Lancet.

Ravinder Dhallen, head of the U.S. company Ravgen, and his team developed the new tool, which detects genetic abnormalities in the fetus by looking for tiny variations in its DNA.

Fetal DNA found in mother's blood sample

It is possible to analyze fetal DNA from a mother's blood sample, but only a small amount of the DNA is found.

The Ravgen technique maximizes the amount of DNA that is recovered by treating the blood samples with a chemical and then looking for a characteristic pattern in the genetic material.

"With further refinement, a prenatal diagnostic test based on the methods [that we have developed] could be a useful complement to currently available prenatal tests," the team concluded.

The technique holds promise, French doctors said in a commentary accompanying the study.

"Dhallan's test is promising and opens a new era in prenatal diagnosis but to be optimally used as a routine prenatal screening or diagnostic test, their findings need to be replicated in a large-scale multi-centre setting," said Alexandra Benachi, of the Hospital Necker-Enfants Malades in Paris, and Jean-Marc Costa, of the American Hospital of Paris.