Autoantibodies to the islet cell antigen SOX-13 are associated with duration but not type of diabetes.
OBJECTIVE
The autoantigen SOX-13 of the SRY-related high mobility group box is a low-frequency reactant in sera from patients with Type 1 diabetes. We further investigated the potential diagnostic role of anti-SOX-13, and in particular its ability to distinguish Type 1 from Type 2 diabetes, in two large, well-characterized cohorts.


METHODS
SOX-13 autoantibody status was ascertained using a radioimmunoprecipitation assay in (i) a random sample of 546 participants in an Australian community-based study (the Fremantle Diabetes Study; FDS) of whom 119 had Type 1 and 427 Type 2 diabetes, and (ii) a sample of 333 subjects with Type 2 diabetes from the United Kingdom Prospective Diabetes Study (UKPDS) stratified by age, anti-glutamic acid decarboxylase (GAD) and islet cell antibody (ICA) status, and requirement for insulin therapy within 6 years of diagnosis.


RESULTS
The frequencies of anti-SOX-13 in the FDS subjects were 16.0% and 14.8% for Type 1 and Type 2 patients, respectively, and levels were similar. In the UKPDS subjects, the frequency was 4.5%. In a logistic regression model involving demographic, anthropometric and metabolic variables, only diabetes duration was significantly associated with anti-SOX-13 positivity, especially for duration > 5 years (P < 0.002). When the coexistence of autoantibodies was assessed in the two study samples, there were no significant associations between anti-SOX-13 and ICA, anti-GAD or ICA512/IA-2.


CONCLUSIONS
Whilst the frequency of anti-SOX-13 may be increased in some populations of diabetic patients, this reactivity does not usefully distinguish Type 1 from Type 2 diabetes. However, the association with diabetes duration suggests that anti-SOX-13 may be a non-specific marker of tissue damage associated with chronic hyperglycaemia.
Davis
T M E
TM
Department of Medicine, University of Western Australia, Fremantle Hospital, Australia. tdavis@cyllene.uwa.edu.au
Mehta
Z
Z
Mackay
I R
IR
Cull
C A
CA
Bruce
D G
DG
Fida
S
S
Rowley
M J
MJ
Holman
R R
RR
D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000097:blood*; D001324:Autoantigens / Q000097:blood*; D015992:Body Mass Index; D015331:Cohort Studies; D003922:Diabetes Mellitus, Type 1 / Q000175:diagnosis* / Q000276:immunology; D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis* / Q000276:immunology; D005260:Female; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000097:blood*; D008875:Middle Aged; D011446:Prospective Studies; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases / Q000097:blood*; D015531:Radioimmunoprecipitation Assay / Q000379:methods; D054635:Receptor-Like Protein Tyrosine Phosphatases, Class 8
D001323:Autoantibodies; D001324:Autoantigens; D008565:Membrane Proteins; C024211:islet cell antibody; C516862:PTPRN protein, human; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases; D054635:Receptor-Like Protein Tyrosine Phosphatases, Class 8