SAA1 and rheumatoid arthritis: Notably, isolated GI involvement without renal disease has been documented only in exceedingly rare instances.[1,2] Rheumatoid arthritis (RA) is the leading cause of AA amyloidosis, whereas spondyloarthritis (SpA), including ankylosing spondylitis (AS), is also implicated less frequently.[3] Interleukin (IL)-6, a key driver of SAA synthesis, plays a central role in the pathogenesis of AA amyloidosis, and its inhibition has demonstrated therapeutic potential.[4]