Anti–Citrullinated Protein Antibodies in Unaffected First‐Degree Relatives of Rheumatoid Arthritis Patients

Abstract

The rate of ACPA positivity in unaffected FDRs of RA patients with a high prevalence of the SE and smoking was 48%, whereas ACPAs were rare in the healthy controls. ACPAs in the FDRs of RA patients was most commonly of the IgA isotype, but IgG ACPA targeting citrullinated vimentin was also frequently found.