Autoantibodies to a nucleolar RNA helicase protein in patients with connective tissue diseases.
OBJECTIVE
An autoantibody to a nucleolar RNA helicase protein (Gu) was recently discovered in a patient with gastric antral vascular ectasia or watermelon stomach, a disorder that is increasingly being described in systemic sclerosis (SSc). The present study was undertaken to determine whether anti-Gu antibodies occur in connective tissue diseases (CTD) and, if so, to determine their frequencies and any clinical or immunogenetic associations.


METHODS
Anti-Gu antibodies were determined by Western blotting of glutathione-purified glutathione S transferase-Gu fusion proteins against consecutive antinucleolar antibody-positive sera (HEp-2 cell substrate) collected over a 5-year period in a rheumatology antinuclear antibody (ANA) testing laboratory.


RESULTS
Anti-Gu antibodies were found in 11 (10%) of 108 antinucleolar antibody-positive sera. The subjects with anti-Gu antibodies included 3 of 46 patients with SSc (7%), 3 of 17 patients with systemic lupus erythematosus (18%), 4 of 9 patients with undifferentiated CTD (44%), and 1 healthy relative of an SSc patient. None of the anti-Gu-positive patients had any symptoms suggestive of watermelon stomach. Increased frequencies of both HLA-DQA1*0501 and DQB1*0301 were found, but only DQB1*0301 maintained statistical significance after correction.


CONCLUSIONS
Anti-Gu (nucleolar RNA helicase) antibodies occur in low frequencies in patients with CTDs who have antinucleolar antibodies by ANA testing, but they are not specific for SSc or the watermelon stomach lesion.
Arnett
F C
FC
University of Texas-Houston Health Science Center, 77030, USA.
Reveille
J D
JD
Valdez
B C
BC
D000328:Adult; D000368:Aged; D000483:Alleles; D001323:Autoantibodies / Q000097:blood; D002352:Carrier Proteins / Q000276:immunology*; D002466:Cell Nucleolus / Q000737:chemistry*; D003240:Connective Tissue Diseases / Q000097:blood / Q000276:immunology*; D005260:Female; D000949:Histocompatibility Antigens Class II / Q000235:genetics; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000097:blood; D008297:Male; D008875:Middle Aged; D050828:Protein Inhibitors of Activated STAT; D012595:Scleroderma, Systemic / Q000097:blood / Q000276:immunology; D025841:Small Ubiquitin-Related Modifier Proteins
D001323:Autoantibodies; D002352:Carrier Proteins; D000949:Histocompatibility Antigens Class II; C106529:PIAS1 protein, human; D050828:Protein Inhibitors of Activated STAT; D025841:Small Ubiquitin-Related Modifier Proteins