Interpretation of top-ranking partial correlation coefficients (PCC>0.5).

Connections between two known metabolites indicate a direct metabolic relationship, e.g. between purines (guanosine/inosine) or steroid hormones (androsterone sulfate/epiandrosterone sulfate). A link between a known and an unknown compound therefore provides evidence for a shared metabolic pathway. For instance, the link between 3-indoxylsulfate and X-12405 suggests a role of this unknown in tryptophan metabolism. Abbreviations: PC = phosphatidylcholine, PE = phosphatidylethanolamine, ζ = partial correlation coefficient. Italic text represents hypothetical known-unknown connections.