SOX13 Autoantibodies Are Likely to Be a Supplementary Marker for Type 1 Diabetes in Korea

: The SOX13, one of the family of transcription factors that play key roles in organ development, is reported to be a diabetes autoantigen, islet cell antigen 12 (ICA12). Recently, a study of antibodies to SOX13 was conducted in patients with type 1 diabetes mellitus (T1DM) indicating that these antibodies potentially identified patients without antibodies to the major T1DM‐associated autoantigens, insulin, GAD, or IA‐2. We know that the prevalence of islet‐specific autoantibodies (GAD, IA‐2) in Korean patients is much lower than that in white patients. It may be possible that other autoantibodies that could be directed to as yet unknown antigen may play a role in Korean T1DM patients. To investigate this, we measured SOX13 autoantibodies applying a radioligand binding assay using in vitro transcribed and translated antigen in 188 T1DM patients (mean duration, 4.2 years) and 64 T2DM patients and compared the results with those of 101 healthy control subjects. SOX13 autoantibodies occurred at a significantly higher frequency among T1DM patients (55/188, 29.3%) than among T2DM patients (4/64, 6.2%) or healthy adult controls (1/101, 1%). The 55 patients with positive SOX13 antibodies had significantly shorter duration of diabetes than SOX13 antibody‐negative patients (3.6 ± 2.8 vs. 4.5 ± 3.9 years; p < 0.05). We could detect a prevalence similar to control in patients with Hashimoto's thyroiditis (4.9%, n= 101) and rheumatoid arthritis (6.7%, n= 89). As a whole, 44 of the 55 patients with SOX13 antibodies had at least one or more other autoantibodies to the major T1DM‐associated autoantigens. However, SOX13 antibodies were the only antibodies detected as positive in 1 of the 11 new‐onset patients. We conclude, therefore, that these antibodies are likely to be one of several epitope‐spreading responses to islet‐ or nonislet‐specific autoantigens seen in the development of T1DM, and they may be used as a supplementary marker for investigating T1DM in Korea.