Increased autoantibodies to SOX13 in Swedish patients with type 1 diabetes.

This article aims to estimate the prevalence of SOX13 antibodies in Swedish patients with type I diabetes and healthy controls. The patients (n = 102; median age 35 years [range, 9-89]) were newly diagnosed with type 1 diabetes in a defined area in southern Sweden during 1995-1998. Islet cell antibodies (ICA) were analyzed with immunofluorescence, while glutamic acid decarboxylase antibodies (GADA), tyrosine phosphatase antibodies (IA-2A), and antibodies against the transcription factor SOX13 (SOX13Ab) were analyzed with radioimmunoprecipitating assays. SOX13Ab were found in 9.8% (10/102) of type 1 patients compared to 2.0% (2/99) in healthy controls (P = 0.033). At least one of the four autoantibodies (ICA, GADA, IA-2A or SOX13Ab) were identified in 67% (68/102) of the patients. Samples positive for IA-2A were only in one case positive also for SOX13Ab. IA-2A-positive patients were often positive also for ICA and GADA (19/27), and the same combination was also common for SOX13Ab-positive patients (6/10). Only 2.0% (2/102) were positive for SOX13Ab alone. ICA, GADA and IA-2A were more frequent in younger patients (:535 years of age) than in older patients, while SOX13Ab showed similar frequency in both groups. We concluded that the frequency of SOX13Ab was significantly increased in Swedish patients with type I diabetes, but that the addition of SOX13Ab to the combination of GADA and IA2-A only increased the sensitivity by 2% for autoimmune diabetes. Therefore, SOX13 could be a minor autoantigen involved in the pathogenesis of type 1 diabetes.