Quebec – August, 2001: Researchers at Hôpital Saint-François d’Assise and Laval University, led by Canadian Genetic Diseases Network investigator Dr. Régen Drouin, today announced results of an important study which identifies the number of fetal cells present in maternal blood during normal fetal development. The findings lay the ground work for developing a non-invasive test for prenatal diagnosis of chromosome anomalies such as Down syndrome.

Down syndrome (or trisomy 21) is the most frequently occurring chromosomal abnormality with a worldwide prevalence of 1 in 700 births. The incidence of Down syndrome increases with advancing maternal age and is particularly marked in offspring of women beyond 35; however, only 25% of affected individuals are born to mothers in this age group. Although Down syndrome offspring have mildly reduced life expectancy, they are subject to a number of developmental disabilities and medical complications. Additionally, prenatal diagnosis for Down syndrome requires invasive and costly procedures such as amniocentesis or chorionic villus sampling which, in up to 1% of cases, results in loss of pregnancy.

In a paper published today in the leading scientific journal Clinical Genetics, Dr. Drouin, his colleagues (Drs. Jean-Claude Forest and Jacques Massé) and their team have established that the total number of male fetal nucleated cells per milliliter of maternal blood was consistent in each woman studied and varied between 2 and 6 cells per milliliter within the group of normal pregnancies, for a pregnancy of 18 to 22 weeks of duration. The scientists believe that, for the first time, the number of fetal cells found in their study accurately identifies the number of fetal cells per ml of maternal blood present during normal fetal development.

The discovery process was made possible because the team used extremely efficient molecular cytogenetic techniques (FISH and PRINS) to individually analyze approximately 300 million cells and repeatedly identify an extremely small number of fetal cells among them. Having now proven that the number of fetal cells in maternal
blood, at a given period, is reproducible and can be assessed by cytogenetic methods, the study leads the way to the development of a non-invasive prenatal diagnosis test for diseases with a chromosomal abnormality, such as Down syndrome.

Said Dr. Ron Woznow, CEO of the Canadian Genetic Diseases Network which has supported the work on trisomy 21 since 1997, “I am extremely pleased that CGDN funding has accelerated the publication of these important results, in particular our strategic granting program which provides critical early-stage support to promising research projects with commercial potential.”