Similarly, a few patients with RA or SpA had antibody responses above the cutoff value for fibronectin-1, laminin B2, or collagen Vα1, and several patients with other connective tissue diseases had positive values for at least 1 of these proteins, including 2 with polymyalgia who had high anti–laminin B2 values. Here, FN1 is linked to rheumatoid arthritis.