To determine the HLA associations of seropositive rheumatoid arthritis (RA) in a Cree and Ojibway population; to determine whether specific alleles distinguish juvenile or adult onset.
HLA-A, B, C, and DRB1 alleles were analyzed in 23 Ojibway and Cree patients with RA seen in a single tertiary care center. Comparisons were made with published results of controls and with results of 18 patients with rheumatoid factor (RF) positive polyarticular juvenile rheumatoid arthritis (JRA) from the same population.
Comparisons among patients with RA, patients with RF positive polyarticular JRA, and controls showed increased frequencies of the RA shared epitope in patients with RA and of DRB1*0901 in patients with seropositive polyarticular JRA, while the frequency of DRB1*08 alleles was decreased in patients with RF positive polyarticular JRA.
In this population, DRB1*0901 may promote while DRB1*08 alleles may protect against a juvenile onset of RA specifically. In contrast, the RA shared epitope may have a greater effect on the risk of adult onset seropositive RA. Due to the small patient numbers, these results require confirmation.