Teraspanin 7 Autoantibodies in Type 1 Diabetes and Latent Autoimmune Diabetes in Adults

Objective: This study aimed to investigate the prevalence of the newly-identified islet autoantibody, tetraspanin 7 autoantibody (TSPAN7A) in Chinese type 1 diabetes (T1D) and Latent Autoimmune Diabetes in Adults (LADA), and the correlation between TSPAN7A and islet function in LADA patients.

Research Design and Methods: Patients with newly onset T1D (n=158), long-lasting T1D (n=157), LADA (n=175), type 2 diabetes (T2D; n=204) and healthy control subjects (n=170) were recruited for the cross sectional study. Another cohort including 46 LADA patients with 3-year follow-up was recruited forthe longitudinal study. TSPAN7A was assayed by luciferase immunoprecipitation system assay.

Results: The prevalence of TSPAN7A in newly onset T1D, non-newly onset T1D, T2D, LADA and healthy control subjects were 25.3% (40/158), 10.2% (16/157), 0.5% (1/204), 21.1 (37/175) and 1.2% (2/170), respectively. Out of the 23 patients with newly onset T1D but negative for GADA, IA2 and ZnT8A, 3 patients were positive for TSPAN7A (13.0%) improving the detection of autoantibodies from 81.6% to 83.5% in T1D. In LADA patients, analysis of logistic regression demonstrated that duration (OR=1.77, P=0.026), GADA titer (OR=2.79, P=0.006) and TSPAN7A (OR=2.86, P=0.034) were the risk factors to islet function while BMI was the protection factor (OR=0.35, P=0.001). In the follow-up study, LADA patients with TSPAN7A showed a worse islet function compared those negative for TSPAN7A after 3-year diagnosis.

Conclusion: TSPAN7A is a novel diagnostic tool for T1D and LADA. Combination of TSPAN7A with other autoantibodies can improve the diagnosis of T1D. TSPAN7A is negatively correlated with islet function in LADA.