Gene-expression profiles that classify and predict APS phenotype. (A) Expression profiles of genes that discriminate between APS and non-APS patients with VTE. Image depicts a group of 50 genes selected to differentiate APS from control. Genes are ordered top to bottom according to regression coefficient. (B) Leave-one-out cross-validation (CV) probabilities of individual samples in our training cohort (n = 57) of APS patients (red) and control patients with VTE without aPLA (blue). The values on the horizontal axis are estimates of the overall metagene score in the regression analysis. The corresponding values on the vertical axis are estimated classification probabilities with corresponding 95% probability intervals marked to indicate uncertainty about these estimated values. The horizontal dashed line represents an arbitrary cutoff value to demonstrate the accuracy of prediction for any given probability of the conditions being compared. (C) Validation of the binary regression model in a blinded independent cohort of 32 subjects (21 patients with APS [red] and VTE, 11 controls [blue] with VTE but without aPLAs).