MEFV and familial Mediterranean fever: The mutations in PSTPIP1 underlying PAPA syndrome trigger hyperphosphorylation and markedly increased binding to Pyrin.38 Consistent with the ex vivo colchicine assay being highly specific to FMF, results from the test showed that PAPA patients clustered separately from patients with FMF, thus confirming that the ex vivo colchicine assay supports reliable discrimination of patients with PAPA and FMF (figure 3A and online supplementary table 3A).