title: Sex determination using free fetal DNA at early gestational ages: a comparison between a modified mini-STR genotyping method and real-time PCR.
abstract: OBJECTIVE
  Recently the use of free fetal deoxyribonucleic acid (DNA) in maternal plasma and serum has been applicable for noninvasive prenatal genetic diagnosis. In this study, we applied a new algorithmic base conventional polymerase chain reaction (PCR) genotyping method and also real-time PCR for detecting fetal X and Y-chromosome sequences in maternal plasma to determine fetal sex in pregnant women in their early gestational ages (5-13 weeks). Finally, we compared the efficiency of each method in sex determination.
  
  
  METHODS
  DNA was extracted from 106 pregnant women and their husbands' blood samples. Fetus mini-short tandem repeat (STR) genotyping was accomplished through amplification of 19 mini-STRs and 3 non-STR markers using conventional PCR followed by polyacrylamide gel electrophoresis analysis. Simultaneously, TaqMan real-time PCR was done with the use of DYS14-specific primers and probe.
  
  
  RESULTS
  In conventional PCR method, 47 cases were diagnosed to be male and 49 to be female. In comparison, real-time PCR amplified DYS14 (Y-marker) sequences in 45 pregnant women plasma samples. Sensitivity and specificity were calculated to be 95.9% and 98% for conventional PCR and 91.8% and 100% for real-time PCR method, respectively.
  
  
  CONCLUSIONS
  According to our study, the conventional PCR method was more sensitive than real-time PCR and it could be employed in future clinical diagnostics singly or in combination with real-time PCR.
authors: Department of Medical Genetics, Shiraz University of Medical Sciences, Shiraz, Iran.
authors: Mohamad Reza
authors: MR
authors: Aghanoori
authors: Homeira
authors: H
authors: Vafaei
authors: Hajar
authors: H
authors: Kavoshi
authors: Sanaz
authors: S
authors: Mohamadi
authors: Hamed R
authors: HR
authors: Goodarzi
mesh_terms: D004247:DNA / Q000097:blood*; D005260:Female; D005333:Fetus; D005838:Genotype; D060005:Genotyping Techniques / Q000379:methods*; D005865:Gestational Age; D006801:Humans; D008297:Male; D018895:Microsatellite Repeats; D011247:Pregnancy; D060888:Real-Time Polymerase Chain Reaction; D012732:Sex Determination Analysis / Q000379:methods*
chemical_list: D004247:DNA