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Fetal fraction in maternal plasma cell-free DNA at 11-13 weeks' gestation: effect of maternal and fetal factors.
Ashoor G, Poon L, Syngelaki A, Mosimann B, Nicolaides KH.
Fetal Diagn Ther 2012;31:237-43. -
Chromosome-selective sequencing of maternal plasma cell-free DNA for first-trimester detection of trisomy 21 and trisomy 18.
Ashoor G, Syngelaki A, Wagner M, Birdir C, Nicolaides KH.
Am J Obstet Gynecol 2012;206:322.