RBP4 and osteoarthritis: Nonetheless, RBP4 has not been studied in the context of crystalline arthropathies, which are a group of inflammatory arthritides associated with crystal deposition in the synovial space including gout, which is common in patients with obesity or metabolic alterations [24], and pseudogout (calcium pyrophosphate dihydrate crystal deposition (CPPD)-mediated disease), which is associated with degenerative joint diseases [25,26].