Distribution of Gm allotypes in juvenile chronic arthritis

The immunoglobulin allotypes G1m(a), G1m(x), G2m(n), G3m(b) and Km(1) were determined in 76 Swedish patients with juvenile chronic arthritis (JCA). Eight of the patients had the systemic form of the disease. 37 belonged to the polyarticular and 31 to the oligoarticular subset. The frequency of the G1ma(x), G3m-b haplotype was significantly increased in the polyarticular subset but not in the oligoarticular subset, compared with the normal population (p less than 0.01). The polyarticular subset also differed from the oligoarticular subset with increased frequency (p less than 0.01) and higher levels (p less than 0.01) of IgM rheumatoid factor and a lower rate of remission (p less than 0.05). The few JCA patients in the systemic subset showed similar features as the polyarticular patients. The frequencies of G2m(n) and Km(1) did not deviate from the expected in any of the JCA subsets.