Systemic lupus erythematosus in three ethnic groups: I. The effects of HLA class II, C4, and CR1 alleles, socioeconomic factors, and ethnicity at disease onset. LUMINA Study Group. Lupus in minority populations, nature versus nurture.

OBJECTIVE

To study the relative impact of immunogenetic versus socioeconomic factors on systemic lupus erythematosus (SLE) at disease onset/presentation.

METHODS

Medical records regarding SLE onset/ presentation were abstracted on 229 SLE patients who were enrolled in a prospective lupus outcome study. Patients were grouped in equivalent proportions of Caucasians, African Americans, and Hispanics. HLA-DRB1, DQA1, and DQB1 oligotyping, as well as C4 and CR1 allotyping, were carried out by standard methods. In addition to these genetic factors, data on ethnicity, age at SLE onset, monthly income, level of education, and home ownership were entered into stepwise logistic or stepwise multiple linear regression models as independent variables, and each specific clinical feature (neurologic, renal, and cardiovascular disease due to SLE), as well as the total Systemic Lupus Activity Measure (SLAM) score and physician's global assessment of disease activity at disease onset, were entered as dependent variables.

RESULTS

HLA-DRB10301 (DR3), DRB11503 (DR2), and DRB108 (DR8) alleles were more frequently found in Caucasians, African Americans, and Hispanics, respectively. Hispanics were more likely to have cardiac and renal disease, as well as a higher physician's global assessment of disease activity. African Americans were more likely to have neurologic disease, renal disease, and a higher SLAM score. Those with less education had a higher SLAM score. Patients with HLA-DRB101 had less renal disease and a lower SLAM score. Those with C4A*3 alleles had a higher SLAM score and a higher physician's global assessment of disease activity.

CONCLUSION

Both genetic and socioeconomic determinants, as well as other factors associated with Hispanic and African-American ethnicity, affect the presentation of SLE.