In the last three decades, out of 77 orphan drug designations, 14 orphan drug approvals were granted by the FDA for the treatment of rare rheumatologic disorders, i.e. juvenile idiopathic arthritis (N = 5), cryopyrin-associated periodic syndromes (N = 3), uveitis (N = 3), familial Mediterranean fever (N = 1), anti-neutrophil cytoplasmic antibody-associated vasculitis (N = 1), and xerostomia and keratoconjunctivitis sicca in Sjögren’s syndrome (N = 1). This evidence concerns the gene NLRP3 and familial Mediterranean fever.