Fetal methylation markers
This application describes the discovery that, in a pregnant woman, certain genes (such as RASSF1A, APC, CASP8, RARB, SCGB3A1, DAB2IP, PTPN6, THY1, TMEFF2, and PYCARD) originated from a fetus are highly methylated, whereas the same genes of maternal origin are unmethylated. This discovery allows the easy detection of one or more of these methylated fetal genes in a biological sample from a pregnant woman, serving as a universal indicator of the presence of fetal DNA in the sample. These fetal methylation markers are particularly useful as positive controls for a non-invasive analytical process during which the quality and quantity of fetal DNA are monitored. These newly identified fetal markers can also be measured directly for diagnosis of certain pregnancy-related conditions.
1. A method for detecting the presence of or an increased risk for developing preeclampsia in a pregnant woman, comprising the steps of:
(a) treating a plasma or serum sample from the woman with an agent that differentially modifies methylated and unmethylated DNA;
(b) determining the amount of methylated DNA sequence of RASSF1A in the sample, and
(c) comparing the amount from step (b) with a standard control,
wherein an increase in the amount from step (b) compared with the control indicates the presence of or an increased risk for developing preeclampsia.
2. The method of claim 1 , wherein the sample is plasma.
3. The method of claim 1 , wherein the sample is serum.
4. The method of claim 1 , wherein the agent digests unmethylated DNA but not methylated DNA.
5. The method of claim 4 , wherein the agent is a methylation sensitive enzyme.
6. The method of claim 5 , wherein the methylation sensitive enzyme is a methylation sensitive restriction enzyme.
7. The method of claim 6 , wherein the methylation sensitive restriction enzyme is Hpa II or BstU I.
8. The method of claim 1 , wherein the agent comprises bisulfite.
9. The method of claim 1 , wherein step (b) comprises an amplification process.
10. The method of claim 9 , wherein the amplification process is a polymerase chain reaction (PCR).
11. The method of claim 10 , wherein the PCR is real-time PCR.