The amount of a phosphoribosyl pyrophosphate synthase-associated protein 1 when measured in blood serum. The trait is level of phosphoribosyl pyrophosphate synthase-associated protein 1 in blood serum (OBA_2043041, an Ontology of Biological Attributes id). Also known as: blood serum phosphoribosyl pyrophosphate synthase-associated protein 1 amount.