Systemic sclerosis in 3 US ethnic groups: a comparison of clinical, sociodemographic, serologic, and immunogenetic determinants.

OBJECTIVE: To determine whether ethnic factors influence the presentation, serologic expression and immunogenetics of systemic sclerosis (SSc), patients from 3 ethnic groups were compared for clinical features, SSc-associated autoantibodies, and human leukocyte antigen (HLA) class II alleles.
METHODS: Fifty-four Hispanics, 28 African Americans, and 79 whites from Texas with recent-onset (less than 5 years) SSc enrolled in a prospective longitudinal study were assessed for sociodemographic, clinical, immunologic, immunogenetic, behavioral, and psychologic parameters using validated instruments and standard laboratory techniques. Serologic and immunogenetic characteristics from these patients and larger retrospective SSc cohorts of the same ethnic groups also were examined.
RESULTS: Hispanics and African Americans in the prospective cohort were more likely to have diffuse skin involvement, skin pigmentary changes, digital ulcers, pulmonary hypertension (African Americans), and an overall lower sociodemographic status than whites, who had more facial telangiectasia and hypothyroidism. In the larger combined prospective and retrospective groups of SSc patients, whites were likely to have more anticentromere antibodies (ACA) and African Americans more anti-U1-ribonucleoprotein (RNP) and anti-U3-RNP (fibrillarin) autoantibodies. HLA-DQB1*0301 was significantly associated with SSc per se in all 3 ethnic groups; HLA-DRB1*11 correlated with the anti-topoisomerase I antibody response, and HLA-DRB1*01, DRB1*04, and DQB1*0501 with ACA.
CONCLUSIONS: Important sociodemographic, clinical, and serologic differences exist between whites, African Americans, and Hispanics, despite shared genetic (HLA class II) predisposing factors. The impact of these differences on prognosis remain to be determined.