Table 3.
Summary of Bisulfite Analysis of the RASSF1A Marker
| Number of clones at designed CpG sites |
|||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| First trimester samples | Methylation status | +157 | +168 | +170 | +177 | +182 | +188 | +195 | +207 | +222 | +225 | +229 | +246 | +248 | +250 |
| I Pla | M | 54 | 55 | 53 | 55 | 50 | 34 | 53 | 49 | 51 | 46 | 58 | 58 | 57 | 56 |
| I Pla | U | 6 | 5 | 7 | 5 | 10 | 26 | 7 | 11 | 9 | 14 | 2 | 2 | 3 | 4 |
| I Mat | M | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
| I Mat | U | 60 | 60 | 60 | 60 | 60 | 60 | 60 | 60 | 60 | 60 | 60 | 60 | 60 | 59 |
| χ2 | 94.58 | 97.88 | 91.38 | 97.88 | 82.32 | 44.69 | 91.38 | 79.47 | 85.25 | 71.39 | 108.42 | 108.42 | 104.8 | 97.44 | |
| P | <.0001 | <.0001 | <.0001 | <.0001 | <.0001 | <.0001 | <.0001 | <.0001 | <.0001 | <.0001 | <.0001 | <.0001 | <.0001 | <.0001 | |
The proportion of methylated (M) and unmethylated (U) clones at each CpG site of the RASSF1A sequence during the first trimester of pregnancy was compared between placental and maternal blood DNA. I Pla: first-trimester placental tissue; I Mat: first-trimester maternal blood cells. The χ2 analysis refers to the comparison within an individual CpG site. Bold numbers indicate the positions of the CpG sites used to design real-time MSP oligonucleotides. ns: not significant.