[Juvenile rheumatoid arthritis and HLA-B27].

Forty children with juvenile rheumatoid arthritis were studied to determine the frequency of the histocompatibility antigen HLA [human leukocyte antigen)-B27 in this disease and to characterize the arthropathy associated with this antigen. HLA-B27 was detected in four patients (10%). Its presence was associated in a statistically significant manner with sacroiliitis demonstrated radiologically and with a greater age at the time symptoms in the joints first appeared; this age was, on average, 10 years, compared with 6.29 years for the children without HLA-B27.