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Table 4 Implementation characteristics of studies

From: Systematic review supports the role of DNA methylation in the pathophysiology of preeclampsia: a call for analytical and methodological standardization

Characteristics n %
Time of sampling
At the time of delivery 82 91.1
Before delivery 13 14.4
After delivery 5 5.5
At the time of abortion 7 7.8
Not reported 7 7.8
Sample
Placenta 75 83.3
Maternal peripheral blood
Plasma 9 10.0
Serum 2 2.2
White blood cells (WBC) 9 10.0
Lymphocytes 1 1.1
Whole maternal blood 1 1.1
Umbilical cord blood 7 7.8
Omental fat arteries 3 3.3
Placental vessels 1 1.1
Umbilical vein 1 1.1
Targeted genetic locations
Global DNA-methylation 5 5.5
Genome-wide 4 4.5
Genome-wide, selected genes for replication 25 27.8
Candidate gene(s) 58 64.4
DNA methylation method (most frequent)
Illumina27+Illumina450 21 23.3
Bisulfite sequencing 23 25.5
Bisulfite pyrosequencing 19 21.1
Methylation specific PCR 11 12.2
Purification of DNA extraction 33 36.7
Validation of methylation 30 33.3