title: Maternal cell-free messenger RNA in twin pregnancies: the effects of chorionicity and severe twin to twin transfusion syndrome (TTTS).
abstract: OBJECTIVE
  To investigate the effects of chorionicity and severe twin to twin transfusion (TTTS) on maternal circulating cell-free messenger RNA (cf-mRNA).
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  A UK tertiary referral Fetal Medicine Center.
  
  
  METHODS
  All monochorionic (MC) twins complicated by severe TTTS (n= 23) and a cohort of uncomplicated dichorionic (DC) (n= 10) and MC (n= 7) pregnancies, between October 2006 and December 2007.
  
  
  METHODS
  Maternal cf-mRNA encoding glyceraldehyde 3-phosphate dehydrogenase (GAPDH), vascular endothelial growth factor receptor 1(VEGFR-1(Flt-1)), vascular endothelial growth factor A (VEGF-A), Endoglin, placental growth factor (PlGF), tyrosine kinase with immunoglobulin-like and EGF-like domains 1 (Tie-1), angiopoietin 1 (Ang-1) and angiopoietin 2 (Ang-2) were measured by a quantitative two-step real-time PCR assay after extraction from maternal plasma.
  
  
  RESULTS
  The amounts of cf-mRNA detectable are reported for uncomplicated DC, MC and TTTS pregnancies, respectively: GAPDH - 80, 100 and 96%; VEGFR-1 - 10, 0 and 26%; VEGF-A- 80, 71 and 96%; Endoglin-70, 71 and 91%; PlGF-70, 57, 26%; Tie-1 0, 43, 0%; Ang-1 71, 50 and 60% and Ang-2 83, 50 and 89%. There was a significant difference in VEGF-A (medians DC -337.3, MC - 390.8, TTTS - 618.6 copies/mL plasma p= 0.024), Endoglin (medians DC-14.49, MC-1171, TTTS - 2896 copies/mL plasma p= 0.027) and Ang-2 (medians DC-13.66, MC-8.49, TTTS 44.80 copies/mL plasma p= 0.007).
  
  
  CONCLUSIONS
  Maternal cf-mRNA could be reliably detected for GAPDH, PlGF, VEGF-A, Endoglin, Ang-1 and Ang-2 in twin pregnancies and a significant difference was demonstrated in VEGF-A, Endoglin and Ang-2 between uncomplicated twins and MC twin pregnancies complicated by TTTS. If such alterations in maternal cf-mRNA precede the onset of clinically apparent disease, this may be used as an adjuvant blood test to complement ultrasound screening.
authors.affiliation: Fetal Medicine Centre, Birmingham Women's Foundation Trust, Edgbaston, Birmingham, UK.
authors.forename: Caroline E
authors.initials: CE
authors.lastname: Fox
authors.forename: Akihiko
authors.initials: A
authors.lastname: Sekizawa
authors.forename: Samantha J
authors.initials: SJ
authors.lastname: Pretlove
authors.forename: Ben C
authors.initials: BC
authors.lastname: Chan
authors.forename: Takashi
authors.initials: T
authors.lastname: Okai
authors.forename: Mark D
authors.initials: MD
authors.lastname: Kilby
mesh_terms: D000328:Adult; D042702:Angiopoietin-2 / Q000097:blood; D015703:Antigens, CD / Q000097:blood; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D002474:Cell-Free System; D002823:Chorion; D015331:Cohort Studies; D000071063:Endoglin; D005260:Female; D005330:Fetofetal Transfusion / Q000097:blood* / Q000175:diagnosis / Q000235:genetics; D006801:Humans; D007231:Infant, Newborn; D011247:Pregnancy; D011446:Prospective Studies; D012333:RNA, Messenger / Q000097:blood*; D060888:Real-Time Polymerase Chain Reaction; D011956:Receptors, Cell Surface / Q000097:blood; D012720:Severity of Illness Index; D014430:Twins, Monozygotic; D042461:Vascular Endothelial Growth Factor A / Q000097:blood
chemical_list: D042702:Angiopoietin-2; D015703:Antigens, CD; D015415:Biomarkers; C064206:ENG protein, human; D000071063:Endoglin; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A