Accuracy of Noninvasive Fetal Sex Determination using fetal DNA

January 01, 0001

Accuracy of Noninvasive Fetal Sex Determination using fetal DNA

Testing for fetal gender can be of use in cases of some heritable disorders. These US researchers examined the accuracy of noninvasive fetal sex determination using cell-free fetal DNA via a systematic review and meta- analysis of English-language human studies in Pubmed. References lists were also searched.

The researchers found: "From 57 selected studies, 80 data sets (representing 3524 male-bearing pregnancies and 3017 female-bearing pregnancies) were analyzed. Overall performance of the test to detect Y chromosome sequences had the following characteristics: sensitivity, 95.4% and specificity, 98.6%, diagnostic odds ratio (OR), 885, positive predictive value, 98.8%, negative predictive value, 94.8%, area under curve (AUC), 0.993, with significant interstudy heterogeneity. DNA methodology and gestational age had the largest effects on test performance. Methodology test characteristics were AUC, 0.988 for polymerase chain reaction (PCR) and AUC, 0.996 for real- time quantitative PCR (RTQ-PCR). Gestational age test characteristics were AUC, 0.989 (<7 weeks), AUC, 0.994 (7-12 weeks), AUC, 0.992 (13-20 weeks), and AUC, 0.998 (>20 weeks). RTQ-PCR (sensitivity, 96.0%, specificity, 99.0%) outperformed conventional PCR (sensitivity, 94.0%, specificity, 97.3%). Testing after 20 weeks (sensitivity, 99.0%, specificity, 99.6%) outperformed testing prior to 7 weeks (sensitivity, 74.5%, specificity, 99.1%), testing at 7 through 12 weeks (sensitivity, 94.8%, specificity, 98.9%), and 13 through 20 weeks (sensitivity, 95.5%, specificity, 99.1%)."

The researchers concluded: "Despite interstudy variability, performance was high using maternal blood. Sensitivity and specificity for detection of Y chromosome sequences was greatest using RTQ-PCR after 20 weeks' gestation. Tests using urine and tests performed before 7 weeks' gestation were unreliable."

Real-time quantitative PCR appears to be an accurate tests for fetal gender after 20 weeks gestation.

For the full abstract, click here.

JAMA 306(6):627-636, 10 August 2011 © 2011 American Medical Association
Noninvasive Fetal Sex Determination Using Cell-Free Fetal DNA. Stephanie A. Devaney, Glenn E. Palomaki, Joan A. Scott, Diana W. Bianchi.

Category: W. Pregnancy, Family Planning. Keywords: gender, sex determination, fetal, non-invasive, cell-free DNA, systematic review with meta-analysis, journal watch.
Synopsis edited by Dr Paul Schaefer, Toledo, Ohio. Posted on Global Family Doctor 26 August 2011

Pearls are an independent product of the Cochrane primary care group and are meant for educational use and not to guide clinical care.

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