Table 2.

Combined digital RMD and NASS for determining the fetal PLAC4 genotype in first trimester maternal plasma

SampleWells*No. negative wellsLAGLALGAGLAGAll DNA
Short DNA
FetalMaternalA + LAG + LGmrFetal %SPRTAGmrFetal %SPRT
  • L, extension product generated only by the long amplicon; A, extension product of the A allele; G, extension product of the G-allele; U, unclassified.

  • *The digital PCR and primer extension reactions were performed in 384-well plates. Extension products were identified by mass spectrometry. Occasionally, the software, SpectroTYPER (Sequenom), that acquired the mass spectrometry data would identify and indicate certain wells as producing a “bad spectrum.” These wells were excluded from further analysis, and therefore the number of digital PCR was not always multiples of 384 wells.

  • Fetal DNA percentage based on the ZFY/X counts from all DNA (long and short) molecules.

  • Fetal DNA percentage based on the ZFY/X counts from the short DNA molecules.