The aims of this study were 2-fold: to investigate whether US subclinical synovitis represents a distinct stage of the ‘continuum’ in second-generation IgG anti-CCP antibody–positive (CCP2+) at-risk individuals prior to the development of clinical inflammatory arthritis and to determine in anti-CCP2+ at-risk individuals with MSK symptoms but before joint involvement (neither clinical nor subclinical synovitis), clinical and/or serological predictors of US subclinical synovitis. This evidence concerns the gene AGBL2 and medullary sponge kidney.