Non-invasive detection of fetal genetic traits

Abstract

Blood plasma of pregnant women contains fetal and (generally >90%) maternal circulatory extracellular DNA. Most of said fetal DNA contains ≦500 base pairs, said maternal DNA having a greater size. Separation of circulatory extracellular DNA of <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 ≦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.

1 . Isolated deoxyribonucleic acid (DNA), consisting of:
 DNA fragments of substantially 500 base pairs or less comprising a fraction of DNA from blood plasma of a pregnant female largely constituted of circulating extracellular fetal DNA,   which DNA fragments are not in association with a gel, and   which circulating extracellular fetal DNA in the isolated DNA is enriched relative to circulating extracellular DNA in the blood plasma of the pregnant female.   
     
     
         2 . The isolated DNA of  claim 1 , wherein the DNA fragments are substantially 300 base pairs or less. 
     
     
         3 . The isolated DNA of  claim 2 , wherein the DNA fragments are at least about 70% circulating extracellular fetal DNA. 
     
     
         4 . The isolated DNA of  claim 1 , wherein the fetal DNA comprises an allele different than an allele in the maternal DNA. 
     
     
         5 . The isolated DNA of  claim 1 , wherein the fetal DNA comprises a chromosome aneuploidy. 
     
     
         6 . The isolated DNA of  claim 1 , wherein the fetal nucleic acid comprises a paternally inherited polymorphism not present in a maternally inherited sequence. 
     
     
         7 . The composition of  claim 6 , wherein the paternally inherited polymorphism is of a length different than in the maternally inherited sequence. 
     
     
         8 . The isolated DNA of  claim 1 , wherein the DNA fragments comprise DNA that can amplify DNA fragments in the isolated DNA. 
     
     
         9 . The isolated DNA of  claim 8 , wherein the DNA fragments comprise a DNA primer that can amplify DNA fragments in the isolated DNA. 
     
     
         10 . The isolated DNA of  claim 1 , wherein the DNA fragments are in solution. 
     
     
         11 . Isolated deoxyribonucleic acid (DNA), consisting of:
 DNA fragments of substantially 500 base pairs or less comprising a fraction of DNA from blood plasma of a pregnant female largely constituted of circulating extracellular fetal DNA,   which DNA fragments are not in association with a gel,   which circulating extracellular fetal DNA in the isolated DNA is enriched relative to circulating extracellular DNA in the blood plasma of the pregnant female, and   which isolated DNA is prepared by a process comprising:   (a) extracting circulating extracellular DNA from the plasma from the pregnant female, thereby providing extracted DNA; and   (b) separating and isolating the extracted DNA by size, thereby providing separated and isolated DNA;   whereby the separated and isolated DNA is enriched for the circulating extracellular fetal DNA.   
     
     
         12 . The isolated DNA of  claim 11 , wherein the DNA fragments are substantially 300 base pairs or less. 
     
     
         13 . The isolated DNA of  claim 12 , wherein the DNA fragments are at least about 70% circulating extracellular fetal DNA. 
     
     
         14 . The isolated DNA of  claim 11 , wherein the fetal DNA comprises an allele different than an allele in the maternal DNA. 
     
     
         15 . The isolated DNA of  claim 11 , wherein the fetal DNA comprises a chromosome aneuploidy. 
     
     
         16 . The isolated DNA of  claim 11 , wherein the DNA fragments comprise DNA that can amplify DNA fragments in the isolated DNA. 
     
     
         17 . The isolated DNA of  claim 16 , wherein the DNA fragments comprise a DNA primer that can amplify DNA fragments in the isolated DNA. 
     
     
         18 . The isolated DNA of  claim 11 , wherein the DNA fragments are in solution. 
     
     
         19 . The isolated DNA of  claim 11 , wherein separating the DNA in step (b) comprises electrophoresis. 
     
     
         20 . The isolated DNA of  claim 11 , wherein separating the DNA in step (b) comprises chromatography.