Blood plasma of pregnant women contains fetal and (generally>90%)
maternal circulatory extracellular DNA. Most of said fetal DNA contains
.Itoreq.500 base pairs, said maternal DNA having a greater size.
Separation of circulatory extracellular DNA of .Itoreq.500 base pairs
results in separation of fetal from maternal DNA. A fraction of a blood
plasma or serum sample of a pregnant woman containing, due to size
separation (e.g. by chromatography, density gradient centrifugation or
nanotechnological methods), extracellular DNA substantially comprising
.Itoreq.500 base pairs is useful for non-invasive detection of fetal
genetic traits (including the fetal RhD gene in pregnancies at risk for
HDN; fetal Y chromosome-specific sequences in pregnancies at risk for X
chromosome-linked disorders; chromosomal aberrations; hereditary
Mendelian genetic disorders and corresponding genetic markers; and traits
decisive for paternity determination) by e.g. PCR, ligand chain reaction
or probe hybridization techniques, or nucleic acid arrays.