Patent ID: 7824876

Claim:
A bioaffinity assay for quantitative determination in a person's sample of free PAPP-A, defined as pregnancy associated plasma protein A (PAPP-A) that is not complexed to a proform of major basic protein (proMBP), wherein an amount of free PAPP-A present in said sample is determined either i) by exposing said sample to a first binder which binds total PAPP-A and to a second binder which is reactive with the proMBP subunit of the PAPP-A/proMBP-complex and detecting total PAPP-A bound to said first binder and detecting PAPP-A complexed to proMBP bound to said second binder in non-competitive sandwich assays, and calculating a difference between measured total PAPP-A and measured PAPP-A complexed to proMBP, or ii) by a direct bioaffinity assay measuring only free PAPP-A, by making PAPP-A complexed to proMBP non-capable of participating in a bioaffinity reaction in which said sample is exposed to a binder which binds total PAPP-A, by pre-absorbing PAPP-A complexed to proMBP by the steps of exposing said sample to a first binder which binds to pro-MBP, allowing said proMBP to bind to said first binder, absorbing said first binder onto a solid phase and separating said first binder and said bound proMBP from said sample, exposing said sample, from which proMBP has been separated, to a second binder which binds total PAPP-A, and detecting the bound PAPP-A, wherein said first binder and said second binder in i) and ii) are both independently either an antibody or antibody fragment.