Abstract
Few large, multi-ethnic studies have examined the clinical and serologic differences between familial and sporadic SLE patients. Understanding these similarities and differences is critical for interpreting genetic studies and developing therapeutic strategies. We compiled information on 1915 patients with SLE in a large multi-racial cohort, including general demographics, pedigree structure and the specific American College of Rheumatology (ACR) criteria met. One patient was randomly selected from each multiplex family for analysis, yielding 554 European-Americans (EA), 373 African-Americans (AA), 193 Hispanics (HI) and 237 patients of other of mixed races. When comparing familial and sporadic patients stratified by race, lupus erythematosus (LE) cells and arthritis were increased in white familial cases (P = 5.5 × 10−6 and P = 0.028, respectively), but no other significant differences between familial and sporadic patients were found. We found that there were profound differences in clinical profiles between races. For example, photosensitivity and malar rash were decreased in AA (P = 1.3 × 10−13 and 1.4 × 10−7, respectively), whereas discoid rash was increased in AA (P = 5.5×10−6). EA had significantly less renal disease (P = 5.4×10−13), proteinuria (P = 4 × 10−12) and anti-Sm (P = 1.7 × 10−12) than AA or HI. We, therefore, conclude that familial and sporadic onset patients may be treated similarly with respect to clinical and genetic studies.