title: Non-invasive detection of fetal trisomy 21 using fetal epigenetic biomarkers with a high CpG density.
abstract: BACKGROUND
  Non-invasive prenatal test of trisomy 21 (T21) is being researched using fetal specific epigenetic biomarkers present in maternal plasma. We applied a methyl-CpG binding domain-based protein (MBD) method based on epigenetic characteristics of fetal specific-methylated regions with a high CpG density in HLCS on chromosome 21 and RASSF1A on chromosome 3 for the non-invasive detection of fetal T21 and estimated the diagnostic accuracy of the method.
  
  
  METHODS
  A nested case-control study was conducted with maternal plasma collected from 50 pregnant women carrying 40 normal and 10 T21 fetuses. A MBD method was used for enrichment of methylated DNA regions in maternal plasma. The levels of methylated HLCS (M-HLCS) and methylated RASSF1A (M-RASSF1A) were simultaneously measured by multiplex qPCR.
  
  
  RESULTS
  Levels of M-HLCS and M-RASSF1A were obtained in all cases. Levels were not different according to fetal gender (p>0.05 in both). The level of M-HLCS was significantly increased in women with a T21 fetus compared with controls (p<0.001). The level of M-RASSF1A was not different between two groups (p>0.05). In non-invasive fetal T21 detection, the specificity of M-HLCS level and the epigenetic-epigenetic ratio (EER) using M-HLCS and M-RASSF1A levels were 82.5% and 92.5%, respectively, at 90.0% sensitivity.
  
  
  CONCLUSIONS
  Our findings suggest that the EER may be useful as a potential biomarker for the non-invasive detection of fetal T21, regardless of fetal gender. The MBD method can be used as an effective tool in the detection of methylated fetal specific markers with a high CpG density in maternal plasma.
authors.forename: Ji Hyae
authors.initials: JH
authors.lastname: Lim
authors.forename: Da Eun
authors.initials: DE
authors.lastname: Lee
authors.forename: Kyeong Sun
authors.initials: KS
authors.lastname: Kim
authors.forename: Hyun Jin
authors.initials: HJ
authors.lastname: Kim
authors.forename: Bom Yi
authors.initials: BY
authors.lastname: Lee
authors.forename: So Yeon
authors.initials: SY
authors.lastname: Park
authors.forename: Hyun Kyong
authors.initials: HK
authors.lastname: Ahn
authors.forename: Si Won
authors.initials: SW
authors.lastname: Lee
authors.forename: Moon Young
authors.initials: MY
authors.lastname: Kim
authors.forename: Hyun Mee
authors.initials: HM
authors.lastname: Ryu
mesh_terms: D000328:Adult; D019540:Area Under Curve; D015415:Biomarkers / Q000097:blood*; D019731:Carbon-Nitrogen Ligases / Q000235:genetics; D016022:Case-Control Studies; D002891:Chromosomes, Human, Pair 21; D002893:Chromosomes, Human, Pair 3; D018899:CpG Islands / Q000235:genetics; D004247:DNA / Q000097:blood; D019175:DNA Methylation; D004314:Down Syndrome / Q000235:genetics / Q000473:pathology; D044127:Epigenesis, Genetic; D005260:Female; D005333:Fetus / Q000378:metabolism*; D006801:Humans; D008297:Male; D011247:Pregnancy; D012372:ROC Curve; D014314:Trisomy; D025521:Tumor Suppressor Proteins / Q000235:genetics
chemical_list: D015415:Biomarkers; C411762:RASSF1 protein, human; D025521:Tumor Suppressor Proteins; D004247:DNA; D019731:Carbon-Nitrogen Ligases; C023312:holocarboxylase synthetases