Racial differences in antinuclear antibody patterns and clinical manifestations of scleroderma

The profile of antinuclear antibodies (ANA) in 49 Thais with scleroderma (systemic sclerosis) was compared with that in 68 white Australians with scleroderma. Forty-eight (98%) of the Thais and all (100%) of the white Australians were positive for ANA, with the majority (100% and 97%, respectively) showing a diffuse speckled pattern of nuclear fluorescence. The distribution of the patterns was different in the 2 races; 35 (71%) of the Thais and 17 (25%) of the Australians showed staining of the nucleolus, and 1 (2%) of the Thais and 35 (51%) of the Australians showed staining of the centromeres. The frequency of precipitating antibodies to extractable nuclear antigens was also strikingly different: 86% in Thais and 26% in Australians (P less than 0.001). Precipitating antibodies to Scl-70 (topoisomerase I), the predominant extractable nuclear antigen in patients with scleroderma, were detected in 37 (76%) of the Thais and 18 (26%) of the Australians, and these were shown by Western blotting to react with the Scl-70 (topoisomerase I)-associated polypeptides. Differences in the frequencies of the ANA specificities in the 2 races were consistent with differences in the clinical manifestations of scleroderma; all of the Thai patients, in contrast to 15% of the Australian patients, had diffuse scleroderma with widespread skin involvement. This suggest that environmental or genetic factors may influence the expression of scleroderma.