We and others have previously shown that the autoantibodyrepertoire in early untreated RA is directed against several categories of antigens, notably some enzymes of the glycolytic pathway such as aldolase, PGK1, glucose-6-phosphate isomerase and ENO1, and chaperones molecules including calreticulin, HSP-60 and BiP [23]. Here, GPI is linked to rheumatoid arthritis.