title: Maternal serum ADAM12s as a potential marker of trisomy 21 prior to 10 weeks of gestation.
abstract: BACKGROUND
  ADAM12s (a disintegrin and metalloprotease) is a placenta-derived glycoprotein that is involved in growth and differentiation and has been shown to be a potential first-trimester and second-trimester marker of trisomy 21 and other aneuploides. Maternal ADAM12s concentrations show a considerable temporal variation with gestational age and in the initial study levels were found to be significantly reduced in the early first trimester. Here we study the levels prior to 10 weeks of gestation to establish further the effectiveness or otherwise of ADAM12s as an early screening marker.
  
  
  METHODS
  Samples collected as part of routine first-trimester screening were retrieved from storage. In total, ten samples from singleton pregnancies with trisomy 21 were identified and were collected between the 8th and 9th weeks of gestation-of these 80% had been identified by combined first-trimester screening. A series of 62 gestational age-matched samples from singleton pregnancies collected during the same period formed the control group. ADAM12s was measured by a new DELFIA assay incorporating two monoclonals (6E6 and 8F8). Results were expressed as multiples of the median (MoM).
  
  
  RESULTS
  The median MoM ADAM12s at a median gestation of 9.3 weeks was 0.61 which was significantly lower than in the controls (p = 0.011) when compared by the Mann-Whitney test. The corresponding median pregnancy associated plasma protein (PAPP-A) was 0.30 and free beta-human chorionic gonadotropin (beta-hCG) 2.02.
  
  
  CONCLUSIONS
  Combining the data from this study and from the only other published study with data prior to 10 weeks suggests that ADAM12s may have the potential as an early screening marker for trisomy 21, but may not be as reduced as first thought.
authors.affiliation: Prenatal Screening Unit, Clinical Biochemistry Department, King George Hospital, Goodmayes, Essex IG3 8YB, UK. KevinSpencer1@aol.com
authors.forename: Kevin
authors.initials: K
authors.lastname: Spencer
authors.forename: Annie
authors.initials: A
authors.lastname: Vereecken
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Cowans
mesh_terms: D051722:ADAM Proteins / Q000097:blood*; D000072199:ADAM12 Protein; D000328:Adult; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D004314:Down Syndrome / Q000097:blood* / Q000175:diagnosis*; D005260:Female; D005865:Gestational Age; D006801:Humans; D008565:Membrane Proteins / Q000097:blood*; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D012680:Sensitivity and Specificity
chemical_list: D015415:Biomarkers; D008565:Membrane Proteins; D051722:ADAM Proteins; D000072199:ADAM12 Protein; C000606480:ADAM12 protein, human