Arthritis & Rheumatism, Volume 60,
October 2009 Abstract Supplement
The 2009 ACR/ARHP Annual Scientific Meeting
Philadelphia October 16-21, 2009.
Risk Factors Associated with Development of SLE Among Anti-RNA Helicase A Positive Patients
Chan, Jason Y. F., Li, Yi, Sobel, Eric S., Segal, Mark S., Bubb, Michael R., Chan, Edward K. L., Reeves, Westley H.
Autoantibodies to RNA helicase A (RHA) is a new serological marker of early stage of SLE. Although anti-RHA appears highly specific for SLE among patients with an established diagnosis, some anti-RHA positive individuals do not meet SLE criteria. We evaluated the clinical association of anti-RHA in unselected patients seen in an autoimmune disease clinic, focusing on identifying risk factors associated with the development of SLE.
Sera from the initial visit of patients seen at our autoimmune disease clinic (n = 1542, including 368 SLE, 105 SSc, 72 PM/DM, 56 RA, 61 Sjogren's syndrome: SjS) were screened by immunoprecipitation (IP) of 35S-labeled cell extract and western blot using anti-RHA reference sera. Levels of anti-RHA in sera from sequential visits were measured based on the integrated density (volume) of the protein band acquired with phosphorimager. Clinical information was from a comprehensive database.
Forty-four anti-RHA positive patients (23 Caucasian, 10 African American, 6 Latin, 2 Mixed, 1 Asian, 2 unknown) were identified. Eighty percent (35/44) of cases had SLE (4 or more of criteria), one case each had SSc-PM overlap and SjS. Demographic information and levels of anti-RHA were comparable between SLE vs. non-SLE groups. Among 7 cases that did not meet any disease criteria, 3 cases had 3 items of SLE criteria. Sixty-seven percent (21/32) of anti-RHA positive SLE were within one year of diagnosis consistent with its association with an early stage of SLE. Levels of anti-RHA were reduced over time in 20/23 SLE whose sequential sera were available; however, the correlation between the disease duration vs. levels of anti-RHA at initial visit was not strong. As a whole, the non-SLE group was characterized by lack of other specific autoantibodies by IP (73% vs. 19% in SLE, p = 0.002). Anti-U1RNP (p = 0.008), Sm, ribosomal P (rP), or La (44, 22, 13, and 16%, respectively) were found only in the SLE group whereas anti-Ro and -phospholipid antibodies were found at similar prevalence in both groups. Anti-dsDNA was rare in non-SLE (11% vs 81% in SLE, p = 0.043). In the SLE group when sequential (>6 month apart) sera were tested, 22% (5/23) of patients developed new autoantibody specificities during follow-up (anti-U1RNP+Sm, anti-rP, and anti-Su, one case each, anti-Ro, 2), within 1 year from initial visit in 4/5 cases and within a year of diagnosis of SLE in 3 cases. None of the non-SLE patients with anti-RHA developed new autoantibodies.
Anti-RHA is highly specific for SLE; however, certain anti-RHA positive cases without other coexisting autoantibodies may not fulfill SLE criteria and have a milder/undifferentiated disease. Anti-RHA positive patients who also have anti-U1RNP, Sm, ribosomal P, or dsDNA may have higher risk of developing SLE.
To cite this abstract, please use the following information:
Chan, Jason Y. F., Li, Yi, Sobel, Eric S., Segal, Mark S., Bubb, Michael R., Chan, Edward K. L., et al; Risk Factors Associated with Development of SLE Among Anti-RNA Helicase A Positive Patients [abstract]. Arthritis Rheum 2009;60 Suppl 10 :908