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.

Purpose:

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.

Method:

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.

Results:

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.

Conclusion:

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
DOI: 10.1002/art.25987

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