title: Standardization non-invasive fetal RHD and SRY determination into clinical routine using a new multiplex RT-PCR assay for fetal cell-free DNA in pregnant women plasma: results in clinical benefits and cost saving.
abstract: BACKGROUND
  Among negative RhD mothers it is essential to know the fetal RhD status in order to avoid the possibility of hemolytic disease of the newborn. In this regard, the detection of fetal DNA in maternal plasma might become a new diagnostic tool. In the current study, we have evaluated the standardization of a Multiplex-PCR targeted towards two exons of the RHD and one SRY gene to monitor RhD negative women. The current study addresses questions concerning feasibility and applicability of this approach into the clinical practice.
  
  
  METHODS
  Both single and multiplex real-time PCRs targeting RHD exons 5 and 7 and SRY were applied for the detection of fetal-specific RHD sequences and sex in maternal plasma. A large cohort of 2127 women was studied between 10 and 28 weeks of pregnancy. 134 of them were used for single TaqMan PCR studies and 1993 were evaluated using Multiplex TaqMan PCR studies. All of them were serologically typed as RhD negative according to Spanish guidelines. Single and multiplex real-time PCR results were compared with postnatal serology and sex identification.
  
  
  RESULTS
  There was a 100% concordance between results obtained with single and multiplex real-time PCR assays. At present, 1012 of the 1993 pregnant women studied gave birth and the results of RHD status obtained with the multiplex TaqMan PCR assay were confirmed postpartum by serological methods showing that sensitivity, specificity, and accuracy of the multiplex assay were 100, 98.6, and 99.3%, respectively. This procedure improved the speed of the assay, avoided over-treatment among RhD negative pregnant women bearing RhD negative fetus, and reduced the requirements for clinical and biological monitoring, resulting in a clinical benefit and cost saving.
  
  
  CONCLUSIONS
  The routine determination of fetal RHD status and SRY in maternal plasma, using multiplex real-time PCR, is feasible. The use of multiplex real-time PCR allows improving the response of the laboratory, saving time and reagent costs, opening the door to a complete automatization of the process.
authors: Department of Clinical Biochemistry, The Virgen del Rocío University Hospital (IBiS/CSIC/SAS/University of Seville), Seville, Spain.
authors: Hada C
authors: HC
authors: Macher
authors: Pilar
authors: P
authors: Noguerol
authors: Pablo
authors: P
authors: Medrano-Campillo
authors: María R
authors: MR
authors: Garrido-Márquez
authors: Amalia
authors: A
authors: Rubio-Calvo
authors: Magdalena
authors: M
authors: Carmona-González
authors: Jesús
authors: J
authors: Martin-Sánchez
authors: José A
authors: JA
authors: Pérez-Simón
authors: Juan M
authors: JM
authors: Guerrero
mesh_terms: D002474:Cell-Free System; D017046:Cost Savings / Q000379:methods*; D004247:DNA / Q000097:blood* / Q000235:genetics; D005260:Female; D005333:Fetus / Q000378:metabolism*; D060005:Genotyping Techniques; D006801:Humans; D011247:Pregnancy; D060888:Real-Time Polymerase Chain Reaction / Q000191:economics* / Q000592:standards*; D012015:Reference Standards; D012204:Rh-Hr Blood-Group System / Q000235:genetics*; D051876:Sex-Determining Region Y Protein / Q000235:genetics*
chemical_list: D012204:Rh-Hr Blood-Group System; C026410:Rho(D) antigen; C497745:SRY protein, human; D051876:Sex-Determining Region Y Protein; D004247:DNA