Fetal cells in the maternal circulation. Technical considerations for practical application to prenatal diagnosis.

Recent advances in cell separation technology and DNA analytic techniques leave little doubt as to the presence of fetal cells in the maternal circulation. The potential of using these cells for genetic analysis is compelling. The practical aspects of establishing a universal method utilizing the new capabilities in clinical practice have not been addressed to date. The major hurdles that still need to be traversed before this technology is universally adopted include the identification of appropriate sampling and separation methods yielding fetal cells amenable to genetic analysis by rapid DNA technologies, clinical studies of appropriate statistical power to validate and compare this approach to current genetic testing, and comparison of this approach to other noninvasive paradigms such as triple screening. Despite the tremendous value of noninvasive genetic screening, the rigorous course required to progress from description of scientific capability to validation of a clinical test must not be ignored or rushed for financial considerations.