Cell-free fetal DNA in maternal blood: evolving clinical applications.

Abstract

N THIS ISSUE OF THE JOURNAL, THE FINDINGS REPORTED in the study by Dhallan and colleagues 1 on enhancing recovery of cell-free DNA in maternal blood have major clinical implications. Developing a reliable, transportabletechnologyforcell-freeDNAanalysisimpacts2crucial areas—prenatal genetic diagnosis and cancer detection and surveillance. In prenatal genetic diagnosis, detecting a fetal abnormality without an invasive procedure (or with fewer invasive procedures) is a major advantage. Likewise incancersurveillance(eg,inpatientswithleukemia),monitoring treatment without having to perform a bone marrow aspiration for karyotype also would be of great benefit. Prenatal genetic diagnosis has been available in the United Statessince1968,whenchromosomalabnormalitiesandmetabolictraitsproveddetectablebyanalysisofamnioticfluidcells obtainedbyamniocentesis.Themostcommonindicationfor prenatal genetic testing is maternal age older than 35 years; other indications include prior trisomic offspring, balanced parental chromosomal rearrangements, or increased risk for a mendelian trait. The standard approach is to offer women either second-trimester amniocentesis or first-trimester chorionic villus sampling, which are comparable or nearly comparable in safety. The high diagnostic accuracy of these techniques must be balanced against the risks of undergoing an invasiveprocedure. 2 Estimatesforprocedure-relatedfetalloss