Antibodies to SOX13 (ICA12) are associated with type 1 diabetes

SOX13 is an islet cell autoantigen (ICA12). identified by antibody screenin g of an islet cDNA library. using sera from patient with Type 1 diabetes. W e ascertained the frequency of antibody reactivity to SOX13 and compared it with other Type 1 diabetes autoantibody reactivities. Antibodies were meas ured by radioimmunoprecipitation (RIP) using S-35 labelled SOX 13 expressed in rabbit reticulocyte lysate. Sera from 109 subjects with Type 1 diabetes . 29 with Type 2 diabetes. 144 with other autoimmune diseases and from 201 controls were tested for anti-SOX13, and results were compared with the fre quency of antibodies: to glutamic acid decarboxylase (anti-GAD), islet cell antigen 512 (anti-ICA512) and islet cell cytoplasm (ICA). Anti-SOX13 were detected in 20 (18.34) of 109 subjects with Type 1 diabetes. and more frequ ently in adults than in children (29% vs 10%). Anti-SOX13 usually occurred with anti-GAD but rarely with anti-ICA512. Seven sera positive for anti-SOX 13 did not react with either GAD. ICA512 or islet cell cytoplasm indicatin g that anti-SOX13 represented a distinct population of antibodies. Reactivi ty to SOX 13 represents a further autoantibody response in adults with Type 1 diabetes and may provide a useful disease marker in subjects in whom oth er autoantibody tests are negative.