For this, the protein amount of TFF3 in healthy human SM was measured and compared to SM of patients suffering from OA or RA revealing a protein amount of 298.4 pg/mg in the healthy group (ranging from 46.5 to 663.0 pg/mg), 473.7 pg/mg (ranging from 141.1 to 1125.3 pg/mg) in case of OA, and 299.3 pg/mg (ranging from 155.9 to 701.8 pg/mg) in case of RA. This evidence concerns the gene TFF3 and rheumatoid arthritis.