While the frequency of positivity for IgG anti-KAc-His2B was significantly lower in the risk-RA cohort compared to the CCP2+ early RA cohort (13% compared to 23%, p=0.001), the IgG anti-KAc-His2B levels were still significantly increased in RA-risk individuals compared to population controls (Table 1 and Figure 3D). Here, AGBL2 is linked to rheumatoid arthritis.