For the discovery cohort, the analytical platform consisted of a 1200 HPLC-system (Agilent) connected on-line to an LTQ Orbitrap Velos equipped with a HESI probe (Thermo Scientific). 5 µl of each sample were injected onto a Kinetex C18 150 × 2.1 mm column, 2.6 µ, 100 Å (Phenomenex) and the following mobile phases were used at a flow rate of 0.4 ml/min: H2O with 0.1% formic acid (A) and 3:1 acetonitrile:isopropanol with 0.1% formic acid (B). The linear gradient was 0 min, 5% B; 1 min, 5% B; 21 min, 95% B; 26 min, 95% B; 26.5 min, 5% B; 33 min, 5% B. MS data was collected in centroid mode between m/z 80-1200 at an Orbitrap resolution of 60,000 using the following ESI settings: Cap Temp, 350; Sheath Gas Flow, 45; Aux Gas Flow, 15; Source Voltage, 3 kV; S-Lens RF Level, 60%.