Figure 4

Comparison based on least squared normalization technique for Down and non-aneuploid pregnancies at 12–14 weeks gestation: A - shows overlaid average mass spectra with bin median as solid shapes and 5 and 95th centiles as whiskers for Down (black squares) and non-aneuploid (red circles) pregnancies at 6,000 to 14,000 m/z. The arrows indicate areas of maximal separation. B - a dot plot of the application of a simple predictive algorithm score called a Down Predictive Score = y(m/z 11400) + y(m/z 9200) / y(m/z 6700) based on the spectral differences of the eight Down syndrome and 39 non-aneuploid samples, indicating potential 100% detection and 0% false positive rate.