French investigators have identified in 70 families a second allele predisposing to a group of inflammatory rhematic diseases—the spondyloarthropathies (SpA). MHC HLA-B27 is associated with all familial SpA—ankylosing spondylitis; reactive arthritis; a subspecies of psoriatic arthritis; arthritis with inflammatory bowel disease; and undifferentiated spondyloarthropathy—but now …