Patients with down syndrome have increased prevalence of rheumatoid factor but not autoantibodies to anti-cyclic citrullinated peptide.

The association between Down syndrome (DS), a genetic disorder resulting from trisomy of the 21st chromosome, and the autoantibodies of rheumatoid arthritis (RA) has been proposed but not unequivocally proven. The aim of this study was to determine whether adult patients with DS present higher levels of anti-cyclic citrullinated peptide (anti-CCP) antibodies and/or rheumatoid factor (RF) than the general population. Our results showed that none of the 68 patients with DS had anti-CCP antibodies, whereas among 204 age- and sex-matched controls these autoantibodies were present in one person. However, DS patients presented a higher number of RF positive cases than controls (11.7% to 3.2% respectively; Fisher's exact test, p = .027). The higher number of RF positive cases in the DS group without increase of anti-CCP antibodies may be indicative of immune disturbances in general rather than RA in these patients. Our study supports the view that RA does not occur with higher frequency in patients with DS than in the general population.