AB0427 ANTI-NOR90 AUTOANTIBODIES: FAVORABLE OR UNFAVORABLE PROGNOSIS?
Authors: C. Valero, J. P. Baldivieso, I. Llorente, E. F. Vicente-Rabaneda, L. Esparcia Pinedo., R. Garcia de Vicuna, M. A. Alfranca, S. Castañeda
Journal: Annals of the Rheumatic Diseases (2021)

Background: Anti-NOR 90 autoantibodies (anti-NOR90 Ab) are autoantibodies that target nucleolar transcription factor 1 or hUBF, involved in transcription of RNA polymerase I. These autoantibodies have been detected in 6.1% of patients with Systemic Sclerosis (SSc), but their clinical or prognostic significance has not been clearly defined. Anti-NOR90 Ab have been mostly associated with limited scleroderma with mild organ involvement and can also be found in other rheumatic diseases such as rheumatoid arthritis, systemic lupus erythematosus or Sjogren’s syndrome. Objectives: The aim of this study was to identify the main clinical characteristics of patients with positive anti-NOR90 in our Centre. Methods: This is a retrospective, descriptive, cross-sectional study of all patients with positive anti-NOR90 Ab between January 2013 and December 2020 in a single center. Autoantibodies testing was performed using Euroimmun EUROLINE SSc profile IgG autoAb assay kit. Patient demographics, clinical characteristics, associated diagnoses, laboratory and immunological findings were collected. Results: We identified a total of 26 patients with at least a positive value for anti-NOR90 Ab (Table 1). In most cases anti-NOR90 patients were ANA positive, predominantly with nucleolar pattern and coexisted with other SSc autoantibodies. 12 patients had rheumatic diseases and two had SSc, both with limited cutaneous SSc and absence of organ involvement. 14 patients had no definite diagnosis. Clinical features of anti-NOR90 patients are represented in Figure 1. Five patients presented Raynaud’s phenomenon, two cases with pathological nailfold capillaroscopy and one patient had SSc. There was no patient with skin ulcers, calcinosis, interstitial lung disease or pulmonary hypertension. Four patients had gastroesophageal reflux disease and one patient presented antral vascular ectasia. Six patients developed some neoplasm. Figure 1. Clinical characteristics of anti-NOR90 Ab patients. Conclusion: In our case series anti-NOR90 Ab were associated with multiple rheumatic diseases with heterogeneity of clinical manifestations. We did not observe a further progression to SSc or presence of organ involvement or severe scleroderma, so these autoantibodies could be related with a favorable prognosis. In contrast with previous reports, a striking association with cancer has been detected in our population. Table 1. Demographic characteristics and main diagnoses of anti-NOR90 positive patients. Characteristics Total Anti-NOR90: 26 patients Sex, n 19 women/ 7 men Age, mean (years) 58,9 IQR [46,3-72,2] Race, n Asian: 1; Hispanic: 7; Caucasian: 18 Smoker, n 3 Positive ANA (&gt;1/160), n Pattern, n 24 7 Homogeneous, 4 Nucleolar, 4 Speckled, 1 Centromere, 5 Speckled -nucleolar, 3 Homogeneous-nucleolar. Positive ENA, n 3 2 Anti-SSA-Ro52 and Ro60, 1 anti-RNP and anti-Sm Systemic sclerosisautoantibodies, n •Anti-Ku: 7 •Anti-U3RNP (Fibrilarin): 6 •Anti-RNA polymerase III: 5 •Anti Th/To: 4 •Anti-centromere: 4 (CENP B +/- CENPA) •Anti-topoisomerase I: 2 •Anti-Ro52: 3 •Anti-PM-Scl: 3 Main diagnosis, n 12 Rheumatic diseases: 2 systemic Sclerosis (2 limited/0 diffuse) 1 rheumatoid arthritis 1 LES 1 Sjögren’s syndrome, 3 undifferentiated conective tissue disease 2 overlap (1 Sjögren + LES, 1 Sjögren + MCTD 1) s: 1 morphea, 1 cutaneous graft versus host disease Neoplasm, n 6: 2 solid organ cancer (bladder, kidney), 1 lung adenocarcinoma, 1 multiple myeloma, 1 acute myeloid leukemia: 1 basal cell carcinoma. Abbreviations: LES: systemic lupus erythematosus; MCTD: mixed connective tissue disease Disclosure of Interests: None declared