Seronegative spondyloarthropathies (SpA) are a family of rheumatologic disorders that classically include: 1. Ankylosing spondylitis (AS). 2. Psoriatic arthritis (PsA). 3. Inflammatory bowel disease (IBD) associated arthritis. 4. Reactive arthritis (formerly Reiter syndrome; ReA). 5. Undifferentiated SpA. . Recently, these disorders have been differentiated further into three additional categories including non-radiographic axial SpA (nr-axSpA), peripheral SpA, and lastly, juvenile-onset SpA. This family of disorders shares several clinical features and has common genetic associations.