January 2001


By Serge B. Melançon, M.D.
Andrea Richter, Ph.D.

The research team on Hereditary Ataxias of the medical genetics laboratory at Saint-Justine's Hospital just accomplished a canadian premiere in pre-natal diagnosis: the direct molecular analysis of amniotic cells for a pre-natal diagnosis of Freidreich's Ataxia.

Up to now, the pre-natal diagnosis for this serious disease involved multiple steps, including the analysis of the patients' and their family's DNA with molecular probes that detect restriction fragments length polymorphism (RFLP).

This method required many weeks of intensive laboratory work. Moreover, the results were not always applicable to pre-natal diagnosis. Thus, it is not surprising to observe that only one result of pre-natal diagnosis based on this method has been published since the localization of the gene for this disease in 1988.

Thanks to the research done in the last year, the team from Sainte-Justine's Hospital benefits from new molecular probes extremely informative, developed in the laboratories of Drs Susan Chamberlain in London and Jean-Louis Mandel in Strasbourg.

Those new markers, located very close to the FA gene, enables us to analyze directly the DNA of people at risk from a very small quantity of cells, such as found in the amniotic liquid.

This is how, in less than two weeks, Quebec researchers were able to complete the molecular study of a family at risk for FA, and to do a pre-natal diagnosis without having to culture amniotic cells, as it is the case for most genetic pre-natal diagnosis.

Instead of waiting 3 or 4 weeks, as it was the case before, the results from the pre-natal diagnosis was transmitted to the couple within 48 hours following the amniocenteses.

This technologic development is a valuable gain for the continuation of research supported by CAFA for identifying the genetic default that causes this disease.