Spearman correlations were analyzed for pairwise combinations of PRAGMA-%Dis (A and B), MetO (measured by HRMS with reference calibration; A and C) and MPO (measured by ELISA; B and C). The correlation results (rho estimate, ρ, and p-value) are inset for each scatterplot. CFSPID patients, identified by newborn screening with later inconclusive diagnosis of disease, are shown in red.