The incidence of rheumatic heart disease is great in Brazil. We analyzed the distribution of human leukocyte (HLA) antigens in a Brazilian population sample with rheumatic fever or rheumatic heart disease, with the aim of better understanding the mechanisms involved.
HLA class I (A, B, and C) and class II (DR and DQ) antigen distribution was studied in 40 patients with diagnosis of rheumatic fever or rheumatic heart disease and compared with a control group of 617 healthy individuals for class I typing, from which 118 were drawn for class II typing. A strong correlation between rheumatic fever and rheumatic heart disease and HLA-DRw53 (72.9% in the disease group versus 39% in the control group: p = 0.00061, relative risk, 4.2; etiologic fraction, 0.43) was found. We also found an increase in the frequency of HLA-DR7 (57.5% in the disease group versus 26.3% in control group: p = 0.00715; relative risk, 3.8; etiologic fraction, 0.56). HLA class I and HLA-DQ typing did not point to any association with these diseases.
HLA-DR7 and HLA-DRw53 are markers for susceptibility to rheumatic fever and rheumatic heart disease in Brazil. These results could be explained by genetic differences resulting from racial or geographical diversity.