Background/Purpose:
HLA-DRB1*08, 11 and 13 are strong risk alleles for various juvenile idiopathic arthritis (JIA) subtypes. We reported that carriage of DRB1*11 and *13 increased the risk for uveitis in Non-Hispanic White children with oligoarticular and polyarticular rheumatoid factor (RF) negative JIA. HLA-B8, in linkage disequilibrium with DRB1*03, was reported in African American children with uveitis. Few studies have investigated the role of HLA-DRB1 alleles in Non-Hispanic African American (NH AA) children with JIA or uveitis. Our objective is to determine the association of HLA-DRB1 alleles in NH AA children with JIA and chronic anterior uveitis (CAU). 

Methods:
We performed high-resolution HLA-DRB1 genotyping to determine the frequency of HLA-DRB1*08,11 and 13 alleles in our AA cohorts. Frequencies were compared among JIA and CAU (JIA-associated uveitis and idiopathic chronic anterior uveitis) groups using Chi-square tests and Exact tests. In addition, we compared the frequency of these alleles in our cohorts to 3734 AA healthy controls from the National Marrow Donor Program (NMDP) using two-sided Z-tests for proportions.

Results:
There were 35 NH AA children (21 JIA and 14 CAU) who were mainly female (51.4%). Of those with JIA, 12 (57%) had extended or persistent oligoarticular JIA, and 9 (43%) had polyarticular RF negative JIA. ANA was positive in 8 (38.1%) JIA children and 2 (40%) JIA-associated uveitis children.

Comparing children with JIA and CAU, there was a clinically significant difference in DRB1*13 (9.5% vs. 35.7%, p = 0.058). (Table 1)

Compared to AA controls, children with JIA had increased DRB1*08 (28.6% vs. 3.3%, p < 0.001) and DRB1*11 (38.1% vs. 13.4%, p <0.001). Children with CAU also had increased DRB1*08 (14.3% vs. 3.3%, p = 0.021) and DRB1*11 (42.9% vs. 13.4%, p = 0.001), which may be due to the JIA diagnosis. (Table 2)   

Children with CAU had clinically significant increased DRB1*13 compared to controls (35.7% vs. 17%, p = 0.067). This was similar to the comparison with JIA children.

Conclusion:
We newly report that carriage of HLA-DRB1*08 or DRB1*11 may increase the risk for JIA and uveitis in NH AA children. Carriage of DRB1*13 may also increase the risk for uveitis, but may be specific to risk for eye disease, independent of arthritis. Further studies in NH AA children should be conducted to investigate the role of HLA-DRB1 in children with JIA and uveitis.