Patent ID: 8563242

Claim:
A method for detecting a chromosomal aneuploidy in a fetus carried by a pregnant woman, comprising the steps of: (a) determining in a biological sample taken from the pregnant woman the amount of a methylation marker of fetal origin, wherein the methylation marker is located on a chromosome relevant to the chromosomal aneuploidy or within a section of a chromosome relevant to the chromosomal aneuploidy, and wherein the methylation marker of fetal origin is distinguished from its counterpart of maternal origin due to differential DNA methylation, wherein the biological sample is maternal whole blood, serum, plasma, amniotic fluid, genital tract lavage fluid, placental-tissue sample, chorionic villus sample, or a sample containing fetal cells isolated from maternal blood; (b) determining the amount of a genetic marker of fetal origin in the sample, wherein the genetic marker is located on a reference chromosome, and wherein the genetic marker of fetal origin is distinguished from its counterpart of maternal origin in the sample due to difference in polynucleotide sequence, or the genetic marker does not exist in the maternal genome; (c) determining the ratio of the amounts from (a) and (b); (d) comparing the ratio with a standard control; (e) detecting the ratio to be higher or lower than the standard control; and (f) detecting the presence of a chromosomal aneuploidy in the fetus carried by the woman.