Objective: To determine whether the association of particular MHC class II alleles and the DRB1 "shared epitope" with disease susceptibility and severity in rheumatoid arthritis (RA) applies to ethnic groups other than Caucasian Americans.
Methods: 67 Hispanic American patients with RA and a similar number of ethnically matched controls were typed for DRB1 using polymerase chain reaction methods. DR4 subtype and DQB1 type were determined for the subjects positive for DR4. Disease severity in the patients with RA was assessed by clinical, radiographic and laboratory variables.
Results: The frequency of DR4 was significantly increased in the subjects with RA compared to the control group. However, the "shared" DRB1 amino acid sequence was relatively infrequent in the Hispanic American patients with RA, and there was no association of specific DR4 or DQ alleles with more severe disease or extraarticular manifestations.
Conclusion: The HLA markers that predict poor prognosis and suggest that more aggressive clinical management may be appropriate in Caucasian American patients with RA may not be useful in other ethnic groups.