Autoantibodies to ICA12 (SOX-13) are not specific for Type I diabetes.
OBJECTIVE
The majority of patients with Type I (insulin-dependent) diabetes mellitus has autoantibodies to insulin, glutamic acid decarboxylase and the tyrosine phosphatase-like protein IA-2. Some patients with Type I diabetes, in particular with adult onset diabetes, have, however, only cytoplasmic islet cell antibodies that could be directed to as yet unknown beta cell autoantigens. Recently, one potential antigen, ICA12, was identified as the high mobility group (HMG) box transcription factor SOX-13. Our aim was to evaluate the diagnostic sensitivity and specificity of autoantibodies to SOX-13 for autoimmune diabetes.


METHODS
Full-length SOX-13 was cloned from human brain mRNA, expressed by vitro transcription/ translation and used to detect autoantibodies by immunoprecipitation and radioligand assay in patients suffering from autoimmune diabetes or non-organ-specific autoimmune diseases.


RESULTS
We found SOX-13 antibodies to be present in 11 of 125 (8.8%) patients with newly diagnosed Type I diabetes and in 3 of 43 (7.0%) patients with latent autoimmune diabetes in adults. There was no association with age, sex and a particular pattern of diabetes-specific autoantibodies. Similar frequencies of SOX-13 antibodies were found in 84 patients with rheumatic diseases (4.0-11.4%) and 211 healthy control subjects (5.2 %).


CONCLUSIONS
Our data indicate that SOX-13 represents a minor target of autoantibodies in patients with autoimmune diabetes. Because SOX-13 antibodies were found not to be disease-specific, we assume they are not helpful in improving the diagnosis and prediction of Type I diabetes.
Steinbrenner
H
H
German Diabetes Research Institute at the University of Duesseldorf, Germany.
Lohmann
T
T
Ostendorf
B
B
Scherbaum
W A
WA
Seissler
J
J
D000293:Adolescent; D000328:Adult; D001323:Autoantibodies / Q000097:blood*; D001324:Autoantigens; D001923:Brain Chemistry; D002648:Child; D002675:Child, Preschool; D003001:Cloning, Molecular; D003922:Diabetes Mellitus, Type 1 / Q000175:diagnosis* / Q000276:immunology*; D005260:Female; D015870:Gene Expression; D006609:High Mobility Group Proteins / Q000276:immunology*; D006801:Humans; D007163:Immunosorbent Techniques; D007223:Infant; D007515:Islets of Langerhans / Q000276:immunology; D008297:Male; D008565:Membrane Proteins / Q000276:immunology; D008875:Middle Aged; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases / Q000276:immunology; D012333:RNA, Messenger / Q000235:genetics; D054635:Receptor-Like Protein Tyrosine Phosphatases, Class 8; D055755:SOXD Transcription Factors; D012680:Sensitivity and Specificity
D001323:Autoantibodies; D001324:Autoantigens; D006609:High Mobility Group Proteins; D008565:Membrane Proteins; D012333:RNA, Messenger; C491720:SOX13 protein, human; D055755:SOXD Transcription Factors; C516862:PTPRN protein, human; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases; D054635:Receptor-Like Protein Tyrosine Phosphatases, Class 8