Antibodies to GAD65 and a tyrosine phosphatase-like molecule IA-2ic in Filipino type 1 diabetic patients

OBJECTIVE - Type 1 diabetes is more prevalent in Europeans than it is in As ians. The disease is associated with autoantibodies to GAD65 and a protein tyrosine phosphatase-like molecule (1A-2). The frequency of GAD antibodies in Asian patients with type 1 diabetes may be lower than that in Europeans. No data are available on 1A-2 antibodies in Asians. We tested antibodies t o GAD65 and 1A-2ic (the intracellular fragment containing the antibody epit ope) in Filipino diabetic patients because this population has mixed Europe an and aboriginal racial origins. RESEARCH DESIGN AND METHODS- A cross-sectional study of antibodies to GAD65 and 1A-2ic was performed on a consecutive series of 91 type 1 diabetic pat ients, 74 type 2 diabetic patients, and 100 control subjects attending a di abetes clinic in Manila, the Republic of the Philippines. All subjects were <40 years of age, with a mean age +/- SD of 24.8 +/- 9.8, 34.3 +/- 5.8, an d 25.8 +/- 8.0 years, respectively. Diagnosis of type 1 diabetes was determ ined clinically and confirmed by baseline C-peptide. RESULTS- Of 91 type 1 diabetic patients, antibodies to GAD65 were detected in 25 (27.4%), but antibodies to 1A-2ic were found in only 8 (8.8%) (P = 0. 002); neither autoantibody was detected in either the type 2 diabetic or co ntrol subjects. Of the 25 recently diagnosed type 1 diabetic patients (dise ase duration <2.0 years), autoantibodies to GAD65 were detected in 14 (56%) , but those to 2A-2ic in only 4 (16%) (P = 0.007); GAD65 antibodies were de tected in only 4 (6%) of 66 patients with a longer disease duration (P = 0. 0004). Comparison with recently diagnosed European type 1 diabetic patients of age and disease duration similar to that of the Filipinos indicated tha t 1A-2ic antibodies, unlike GAD antibodies, were significantly less prevale nt in Filipino type I diabetic patients (P = 0.0007). CONCLUSIONS- This is the first study investigating the prevalence and patte rn of humoral immune response in type 1 diabetic patients from the Philippi nes. Antibodies to 1A-2ic, unlike GAD antibodies, were infrequent. Patterns of immune responses to type 1 diabetes-associated antigens may differ worl dwide, with important implications for prediction of the disease and the po tential for antigen-specific therapy.