Background/Purpose: Many systemic autoimmune diseases share heritable and non-heritable risks, as well as some clinical manifestations. A recent meta-analysis based upon genome-wide genetic studies contrasting and comparing a number of major autoimmune diseases revealed expected and unexpected heritable correlations among different diseases and highlighted the exceptional genetic complexity of human autoimmune diseases even without evaluating the similarities and dissimilarity in clinical prevalence and manifestations. Here, we surveyed systemic lupus erythematosus (SLE) patients and their family members from lupus family registry and repository (LFRR), as well as unrelated unaffected healthy individuals (HC) in attempt to provide valuable insights into the effects of heritable and non-heritable factors on pathogenesis of many of these autoimmune diseases.

Methods:

To assess the concurrency of SLE, rheumatoid arthritis (RA), hypothyroidism, Type I diabetes, systemic sclerosis (SSc), and Sjogren’s syndrome (SS) in this collection by surveying 3203 African Americans(AA), 4950 European Americans (EA), and 741 Hispanics (HIS). ACR >= 4 was used to identify SLE patients as well as the family members of the SLE patients. Self-reported RA was further verified by anti-CCP⁺, anti-RF⁺, and DMARD usage. Self-reported Sjogrens was confirmed by anti-Ro and/or anti-La. Self-reported hypothyroidism was verified by usage of exogenous thyroid hormones. Self-reported Type I diabetes was further confirmed by usage of Insulin. Proportionality, chi-square, and mixed regression tests were used to analyze prevalence differences of concurrent autoimmune diseases, as well as to detect gender effects among different populations.

Results:

 In EA, SLE patients were more likely to also meet RA criteria [p<0.01; OR (95% CI), 108.03 (26.45 – 441.19)], SS (p<0.01; 120.18, 16.67 – 866.69), SSc (p<0.01; 36.05, 4.95 – 262.56), and Hypothyroidism compared to HC. Family members of EA SLE patients were also more likely to have RA (p<0.05; 5.55, 1.33 – 23.06), SS (p=0.07; 6.40, 0.86 – 47.47), as well as hypothyroidism compared to HC. However, there was no enrichment of Type I Diabetes in EA family member of SLE patients. AA SLE patients were also more likely to concurrently meet criteria for RA (p<0.01; 142.61, 30.53 – 666.23), SS (p<0.01; 27.62, 5.79 – 131.82), or SSc (p<0.01; 7.19, 2.21 – 23.42) compared to AA healthy controls. Additionally, AA family members of SLE patients were more likely to meet RA criteria (p=0.07; 3.93, 0.88 – 17.66) compared to AA healthy control population. Finally, in the HIS population, SLE patients were more likely to also meet criteria for SS (p<0.01; 29.46, 3.97 – 218.26). No enrichment of assessed autoimmune diseases were noted in HIS family members of SLE patients. The prevalence of majority autoimmune diseases observed in this study is comparable to published works.    

Conclusion: In conclusion, genetically similar autoimmune diseases such as RA, SLE, SS, and SSc had higher concurrent prevalence in SLE patients and their family members compared to more genetically distant autoimmune disease like Type I Diabetes and hypothyroidism.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/familial-aggregation-of-rheumatoid-arthritis-sjogrens-syndrome-and-systemic-sclerosis-were-detected-in-systemic-lupus-erythematous-families/